Artemisia princeps, Artemisia japonica (Western Artemisia), Artemisia rupestris (Bitter Artemisia), and Artemisia velutipes (Matricaria) all belong to the Artemisia genus of the Asteraceae family. Many species are extremely common perennial herbs that grow dominantly in small vacant lots from urban areas to mountainous fields. A major characteristic is that the underside of the leaves is cottony and fluffy, and unusually for the Asteraceae family, they are wind-pollinated. However, because their flowers and fruits are inconspicuous, classification is difficult, and they can be hard to distinguish in the wild. The Artemisia genus is a very large group, so you need to consult a field guide for accurate identification, but for the four species, you can roughly distinguish them by the shape of the leaves and the amount of hair. Three of the species are rare on Honshu, with Artemisia princeps being almost dominant. Nowadays, their use seems to be limited to mugwort rice cakes, but Artemisia japonica is commonly used in Okinawa, and the group is actively researched for its medicinal properties. It can also be used in moxibustion. This article will explain the classification, morphology, ecology, and uses of the Artemisia genus.

What are mugwort, wormwood (Artemisia princeps), bitter wormwood, and male wormwood?

Artemisia indica var. maximowiczii, also known as mugwort, is also called Kazuzaki mugwort or mochigusa. While Artemisia princeps is sometimes seen used online, it is a synonym (former scientific name). It is a perennial herb distributed in Honshu, Shikoku, Kyushu, and the Ogasawara Islands of Japan, as well as in Korea, and grows in a wide range of areas from urban centers to mountains and fields (Kanagawa Prefecture Flora Survey Association, 2018).

Artemisia indica var. indica, also known as Okinawa mugwort or Fuchiba, is a perennial herb distributed in Honshu (west of the Kanto region), Kyushu, and the Ryukyu Islands in Japan; Korea, China, Taiwan, Southeast Asia (Thailand, Cambodia, Myanmar, Vietnam, Philippines), and South Asia, growing in areas such as construction sites and slopes along forest roads (Shimotsuke, 2014).

Artemisia absinthium, also known as bitter wormwood, is a perennial plant native to Europe, Russia, the Caucasus, West Asia, and North America, and has escaped cultivation and become naturalized all over the world, including Japan.

Artemisia japonica subsp. japonica var. japonica, also known as male mugwort, is a perennial herb distributed in Hokkaido, Honshu, Shikoku, Kyushu, and the Ryukyu Islands in Japan; as well as in Korea, China, Taiwan, the Philippines, and Afghanistan. It grows in riverbeds, grasslands, forest edges, and railway embankments. Its Japanese name is said to originate from the small size of its seeds.

All of these belong to the Artemisia genus of the Asteraceae family, and are extremely common perennial plants that predominantly grow in small vacant lots from urban areas to mountainous fields. However, Artemisia wormwood is an introduced species.

Morphologically, the underside of the leaves is cottony and fluffy, and the flower heads (inflorescences characteristic of the Asteraceae family) are usually oriented downwards (rarely upwards) and composed of tubular florets.

The most distinctive feature is that while most plants in the Asteraceae family are insect-pollinated, attracting insects with bright colors for pollination, Artemisia species have tubular florets that are wind-pollinated, relying on the wind to carry their pollen.

One theory suggests that this characteristic evolved when the ancestors of the Artemisia genus, which are closely related to the Chrysanthemum genus, moved into arid regions with fewer insects and switched to wind-pollinated flowers.

In fact, this aligns with the fact that Artemisia species can adapt and grow even in dry, concrete-filled areas.

Mugwort and its relatives have a long history of being used for food and medicine. Although they can be found everywhere these days, it seems that their use has decreased. However, I think most Japanese people have eaten mugwort mochi, which is made from mugwort. In Okinawa, mugwort is called "fuuchiba" and, despite its distinctive taste, is commonly eaten.

In addition, Artemisia princeps is also edible, but distinguishing between these plants is often very difficult in the wild, partly because their flowers are inconspicuous and their characteristics are hard to see.

What are the differences between mugwort, wormwood (Artemisia princeps), bitter wormwood, and male wormwood?

There are approximately 30 species of Artemisia in Japan alone, making it quite difficult to distinguish between them.

However, for reference purposes, we will only consider methods of distinguishing between four species here. Among these four species, *Artemisia princeps* and *Artemisia rupestris* can be clearly distinguished by carefully observing their leaves (Kanagawa Prefecture Flora Survey Association, 2018).

First, while mugwort, wormwood, and bitter wormwood have pinnately compound leaves, meaning the leaves are finely lobed like bird feathers, in contrast to muscovado, where the central leaves have shallower lobes and are usually spatulate-wedge shaped. There is a great deal of variation in the leaves, so you will need to examine several leaves, but it should be relatively easy to identify.

Furthermore, while white hairs are prominent on the leaves of Artemisia princeps, Artemisia japonica, and Artemisia glabra, there are almost no white hairs on Artemisia japonica.

Another important taxonomic difference is that while Artemisia princeps, Artemisia japonica, and Artemisia glabra produce both female and hermaphroditic flowers, Artemisia rupestris produces only female flowers and not hermaphroditic flowers. However, confirming this is limited to the flowering season and would be difficult for the average person.

Regarding the remaining three species, the differences are that in Artemisia princeps and Artemisia japonica, white hairs grow only on the underside, the pinnately compound leaves are not very finely divided, and the tips of the compound leaves are relatively sharp, while in Artemisia rupestris, white hairs grow on the upper surface as well, the pinnately compound leaves are more finely divided, and the tips of the compound leaves are relatively rounded.

Therefore, you can clearly see that wormwood is whitish in appearance.

The two species mentioned above are overwhelmingly rarer than mugwort, and the dominant species growing in towns is usually mugwort.

Artemisia japonica is more resistant to salt and drought damage than Artemisia sulphureus and can be found growing on coastlines (Iriyama, 2006).

What is the difference between mugwort and yomogi (Erigeron annuus)?

The most difficult to grow are mugwort and aster.

The only difference between Artemisia princeps and Artemisia japonica, according to field guides, is that Artemisia princeps has flower heads that are 1.2–1.8 mm in diameter, while Artemisia japonica has flower heads that are 1.8–2.5 mm in diameter. In other words, the parts that look like flowers (which are actually clusters of flowers) are larger in Artemisia princeps.

Therefore, it may be almost impossible to distinguish them outside of their flowering season.

While *Erigeron annuus* is sometimes described as a variety with wider leaf lobes, which could potentially help distinguish it, there is no specific description of how wide the leaf lobes must be to identify *Erigeron annuus*.

From a distribution standpoint, it seems that we can currently confirm that the plants found east of the Kanto region in Honshu are Artemisia princeps, while those found in Okinawa are Artemisia nipponica.

However, there is a clear difference in taste; Western mugwort is less bitter and has a softer texture, making it more suitable for eating.

While distinction is important from a culinary standpoint, mugwort and wormwood are broadly considered varieties within the species Artemisia indica. In some countries and eras, classifications treat mugwort, wormwood, and Artemisia japonica as a single species, indicating that they are an extremely closely related group (Shimono, 2014).

Are there any other similar species?

As mentioned above, there are many varieties, but if you carefully examine the shape of the leaves, you'll find that there are surprisingly few similar species. Nevertheless, you might still find it quite difficult.

Artemisia montana resembles mugwort and magnolia, but unlike them, it has almost no pseudostipules at the base of the petiole, and its flower heads are bulbous and bell-shaped. "Pseudostipules" are leaf-like structures that extend to the left and right from the base of the petiole on the plant body. This is relatively easy to identify, but the flower heads are frankly too ambiguous. It is common in Hokkaido and is usually found in high-altitude mountainous areas on Honshu, so those found in lowlands are likely to be large-sized mugwort.

Artemisia japonica var. lacinifolia resembles Artemisia japonica, but unlike Artemisia japonica, its leaves are pinnately deeply lobed, and the lobes are linear-lanceolate.

Gray wormwood (Artemisia sieversiana) resembles bitter wormwood, but unlike bitter wormwood, its leaf lobes gradually narrow and have sharp tips.

Artemisia vulgaris resembles mugwort and asterias, but is not currently listed in Japanese botanical guides. However, overseas studies have indicated its distribution in Japan, and its actual distribution is still not well understood (Shimono, 2014).

What are the differences in how to use mugwort, wormwood (Artemisia princeps), bitter wormwood, and male wormwood?

What are some uses for mugwort?

Mugwort has a distinctive aroma, and the young shoots picked in spring can be boiled and used in dishes such as blanched greens, soups, or even in kusa mochi (mugwort rice cakes) or deep-fried (Odachi & Hiyama, 2013). It can also be used to make mugwort tea.

Kusa mochi (known as yomogi mochi in the Kansai region) is said to have originated in the Heian period as a rice cake kneaded with cudweed, one of the seven spring herbs, but by the Edo period, the use of mugwort became established (Yamashita, 2019).

Moxibustion, or "kyu," uses moxa, which is an important part of the traditional East Asian medicine practice. Moxa is made from dried mugwort leaves with the downy hairs on the underside (Oda, 1984; Odachi & Hiyama, 2013). In this practice, moxa is burned on selected areas of the body surface (skin) to provide thermal stimulation, which is used for disease prevention and treatment. However, Artemisia montana (Japanese wormwood) is also used in some cases. Furthermore, since the plant distributed in China is not mugwort but Korean wormwood (Artemisia argyi), it is highly likely that this is used in countries other than China.

It has many medicinal uses, and its leaves are used as a crude drug called "gaiyo," which has hemostatic properties. Some of the gaiyo is actually mugwort, which is called Korean mugwort in China.

Young shoots and budding plants, after being dried and brewed into a tea, are traditionally used as a folk remedy for stomach ailments, abdominal pain, diarrhea, anemia, and cold sensitivity. More mature plants are also dried and added to bathwater as a bath additive to relieve lower back pain and hemorrhoids.

Mugwort is known to be highly nutritious, particularly rich in minerals and vitamins. Among vegetables, it ranks third in potassium content (after Swiss chard and parsley), second in iron content (after parsley), and eighth in beta-carotene content (Ando et al., 2022). Furthermore, mugwort is known to have strong antioxidant properties due to its high content of vitamins and polyphenols.

Its unique components include cineole, thujone, β-caryophyllene, borneol, and camphor (Odachi & Hiyama, 2013).

How can I use Artemisia princeps?

Although *Artemisia princeps* has a different distribution than *Artemisia japonica*, and is therefore used in different regions, its uses are very similar to those of *Artemisia princeps*.

In the Western Himalayas, it is called "thitepati" and is used by indigenous people to treat indigestion, chronic fever, and other liver diseases (Koul et al., 2017). In Nepal, the juice of this plant is used to treat dysentery, abdominal pain, and diarrhea. The young leaves are cooked and eaten with barley, adding color and flavor to rice.

For food, the Garo people (a tribe living in the Noklek Biosphere Reserve in Meghalaya, India) eat the tender sprouts as a vegetable.

Nepalis use the juice of the leaves to treat skin diseases, and the dried leaves and flowers are used as an insect repellent.

In Okinawa, it is called Fuchiba, and in the Ryukyuan language, it means "ba (leaf) that cures Fuchi (wind: illness)," which translates to "wind leaf" in Japanese. It has been widely used in households as a medicinal herb because it is believed to be effective in reducing fever, gastrointestinal diseases, and gynecological diseases (Japan Society for Food Science and Technology, 2021).

In cooking, it is often used in dishes such as Fuchiba Jushi (rice cooked with mugwort) and Boroboro Jushi (rice porridge with mugwort) (Watanabe, 2008; Japan Society for Food Science and Technology, 2021). Jushi refers to rice porridge. Its use varies by region.

In addition, it is sometimes added raw to Okinawa soba, and when used in hijaa-jiru (goat soup), it serves to mask the odor.

The reason why Artemisia japonica can be readily eaten raw may be because its leaves are more fragrant than those of Artemisia sylvestris (Yamashita, 2019) and easier to eat.

Chemically, it contains volatile oils such as β-thujone, hernialin, 1,8-cineole, estragole, savinyl acetate, ciscrisanthenyl acetate, dabanone oil, and terpineol, and possesses antifungal properties (Koul et al., 2017). Two novel compounds, trans-ethyl cinnamate and piperitone, have been isolated by chromatographic distillation.

How can wormwood (Artemisia princeps) and mugwort (Artemisia rupestris) be used?

Wormwood is an introduced species and therefore has no traditional uses in Japan, but it has a history of being used in Europe and Turkey for medicinal purposes similar to mugwort (Koul et al., 2017). It is too bitter to eat raw and is used in the herbal liqueur "absinthe."

Scientifically, its antiparasitic, antibacterial, antioxidant, and hepatoprotective properties have been proven, and experimentally, wormwood essential oil has shown antibacterial activity against budding yeast and Candida albicans.

Although Artemisia princeps is not widely used in Japan, the same subspecies found overseas has been widely used in folk medicine to treat eczema and fever.

How is pollination done?

Artemisia plants typically produce large conical inflorescences at the tips of their stems, bearing numerous small flower heads that hang downwards. The flower head is a structure unique to the Asteraceae family; it is not a single flower, but rather an inflorescence (a cluster of flowers). It consists of countless tiny flowers (florets) that may possess stamens and pistils.

There are two types of florets: ray florets and disc florets. However, in mugwort, only disc florets are present, and within these disc florets, the inner part of the flower head contains bisexual flowers (with both stamens and pistils), while the outer part contains female flowers (with only pistils).

As mentioned above, it is unusual for a member of the Asteraceae family to be wind-pollinated (Shimono, 2014; Yamashita, 2019). However, insect-pollinated varieties were also confirmed in 2022 (Hussain et al., 2024).

Regarding pollen, while animal-pollinated pollen sometimes has spines on its surface, Artemisia pollen is smooth, which is thought to be advantageous when dispersed by wind (Bolick, 1990).

What are the seed dispersal methods?

The fruits of the Artemisia genus are obovate achenes, glabrous or hairy. They lack pappus or have very short hairs. The seeds are contained within the very small achenes, resulting in a very high yield.

Therefore, it is thought that there is no special method of seed dispersal, but because the fruit and the seeds inside are very small and the yield is very high, it is thought that, at least in the case of wormwood, it is easily dispersed by water and animals in addition to gravity (Goud et al., 2015).

References

Ando, Masaya; Ogata, Ayano; Kuronuma, Takanori; Matsumoto, Takeshi; and Watanabe, Hitoshi. (2022). Evaluation of domestically produced mugwort varieties for food use. Journal of the All Japan Acupuncture and Moxibustion Society, 72 (1), 68-78. https://doi.org/10.3777/jjsam.72.68

Bolick, MR (1990). The pollen surface in wind-pollination with emphasis on the Compositae. In M. Hesse, & F. Ehrendorfer (Eds.), Plant Systematics and Evolution Vol. 5: Morphology, Development, and Systematic Relevance of Pollen and Spores (pp. 39-51). Springer. https://doi.org/10.1007/978-3-7091-9079-1_4

Goud, BJ, Dwarakanath, V. & Swamy, BC (2015). A review on history, controversy, traditional use, ethnobotany, phytochemistry and pharmacology of Artemisia absinthium Linn. International Journal of Advanced Research in Engineering and Applied Sciences, 4 (5), 77-107. https://indianjournals.com/article/ijareas-4-5-008

Hussain, M., Thakur, RK, Khazir, J., Ahmed, S., Khan, MI, Rahi, P., … & Mir, BA (2024). Traditional uses, phytochemistry, pharmacology, and toxicology of the genus Artemisia L.(Asteraceae): A high-value medicinal plant. Current Topics in Medicinal Chemistry, 24 (4), 301-342. https://doi.org/10.2174/1568026623666230914104141

Iriyama, Yoshihisa. (2006). Artemisia japonica. Journal of the Japanese Society of Landscape Architecture, 31 (4), 449. ISSN: 0916-7439, https://www.jsrt.jp/pdf/dokomade/31-4otokoyomogi.pdf

The Japanese Society for Food Science and Technology. (2021). Traditional Japanese Home Cooking: Donburi, Zosui, and Okowa. Agricultural, Forestry and Fisheries Culture Association. ISBN: 9784540191824

Kanagawa Prefecture Flora Survey Association. (2018). Kanagawa Prefecture Flora 2018 Electronic Edition. Kanagawa Prefecture Flora Survey Association. ISBN: 9784991053726,https://flora-kanagawa2.sakura.ne.jp/efloraofkanagawa.html

Koul, B., Taak, P., Kumar, A., Khatri, T., & Sanyal, I. (2017). The Artemisia genus: A review on traditional uses, phytochemical constituents, pharmacological properties and germplasm conservation. Journal of Glycomics & Lipidomics, 7 (1), 142. https://doi.org/10.4172/2153-0637.1000142

Odachi, Junko & Hiyama, Keiichiro. (2013). On the effects and uses of mugwort (Artemisia princeps). Tezukayama University Faculty of Contemporary Life Studies Bulletin, 9, 1-9. ISSN: 1349-7073, https://tezukayama.repo.nii.ac.jp/records/777

Oda, Ryuzo. (1984). Research on moxa (I): Recent manufacturing processes and the raw material, mugwort. Journal of the All Japan Acupuncture and Moxibustion Society, 33 (4), 427-430. https://doi.org/10.3777/jjsam.33.427

Shimono, Yoshiko. (2014). Artemisia indica Willd. var. maximowiczii (Nakai) H. Hara: From the perspective of a greening plant. Grass and Greenery, 6, 23-31. https://doi.org/10.24463/iuws.6.0_23

Yamashita, Tomomichi. (2019). Mugwort in Everyday Life. Nature Conservation, 568, 18-19. ISSN: 0386-4138, https://www.nacsj.or.jp/magazine/14752/

Watanabe, Yoshio. (2008). Dictionary of Okinawan Folklore. Yoshikawa Kobunkan. ISBN: 9784642014489

Linaria japonica, Linaria verum, and Linaria serrata all belong to the Plantaginaceae family and are herbaceous plants that bear cute, blue-colored "lip-shaped flowers" (flowers with separate upper and lower lips) with a swollen lower lip. Although they are introduced species, they are frequently seen in urban areas, and you might get confused if you only focus on the flowers. However, if you observe the flower color and leaf shape, you will see that they are clearly different. The flowers are very conspicuous, but surprisingly, the rate of self-pollination is high, and it is thought that almost all species in the Linaria genus are self-pollinating. This article will explain the classification, morphology, and ecology of the Linaria and Linaria genera.

What are *Linaria japonica*, *Linaria cantoniensis*, and *Linaria thunbergii*?

Nuttallanthus canadensis, also known as pine-leaved toadflax, is an annual plant native to the Americas (Canada to Argentina) that has naturalized in Japan (west of the northern Kanto and Hokuriku regions), Russia, India, and Korea (RBG Kew, 2026). It was first collected in Kyoto City in 1941 (Shimizu et al., 2001), and quickly naturalized in port areas along the Kinki region and the Seto Inland Sea, spreading northward between 1988 and 2001 (Kanagawa Prefecture Flora Survey Association, 2018).

Nuttallanthus texanus, also known as large-leaved toadflax, is an annual plant native to North America (Canada and the United States) that has naturalized in Japan and northern South America. Its distribution within Japan is unclear due to ambiguity in distinguishing it from Toadflax japonica (Kanagawa Prefecture Flora Survey Association, 2018), but it may resemble Toadflax japonica.

Cymbalaria muralis, also known as ivy-leaved toadflax, is a climbing perennial plant native to the Mediterranean region (France, Switzerland, Italy, Austria, and the former Yugoslavia) and has naturalized worldwide, including in Japan. In Japan, it was introduced during the Taisho era (1912-1926) for ornamental purposes and planted in rock gardens, but escaped cultivation and naturalized, growing along roadsides and in crevices of stone walls in residential areas throughout Hokkaido and Honshu (Shimizu et al., 2001).

All of these plants belong to the Plantaginaceae family and share the common characteristic of being herbaceous plants that bear "lipped flowers" (flowers with separate upper and lower lips) with a swollen lower lip in the center, often in shades of blue. These swollen labiate flowers are also called "mask-shaped corollas" or "mask-shaped flowers."

Other morphological features include a bifurcated upper lip of the corolla and an elongated spur at the base of the corolla.

Although it's an introduced species, it's frequently seen in urban areas, but if you only focus on the flowers, you might get confused.

What are the differences between *Linaria japonica*, *Linaria cantoniensis*, and *Linaria scabra*?

As a fundamental point, while *Linaria japonica* and *Linaria canadensis* belong to the genus *Linaria*, *Linaria scaber* belongs to the genus *Linaria japonica*.

Therefore, there are significant differences both morphologically and ecologically (Kanagawa Prefecture Flora Survey Association, 2018).

While *Linaria japonica* and *Linaria japonica var. japonica* are annuals with cylindrical stems, linear leaves, and blue flowers, *Linaria thunbergii* is a perennial with thread-like stems, palmate leaves, and purple flowers.

The term "palmate" means "hand-shaped," and in *Linaria japonica*, the leaves are clearly spread out like a palm, but in *Linaria japonica* and *Linaria verum*, they are not, and are closer to ordinary leaves that we commonly see.

Because the ivy-leaved toadflax is specialized to creep along the ground in the gaps of stone walls, its stems are extremely thin.

The field guide states that the difference between Linaria japonica and Linaria maximowicziana is that in Linaria japonica, the corolla (excluding the spur) is 6-10 mm long and the fruit has scattered projections, while in Linaria maximowicziana, the corolla (excluding the spur) is 10-14 mm long and the fruit has densely packed projections.

However, this alone might feel a little vague.

Further comparison reveals that while *Linaria japonica* produces 1 to 4 (up to 7) flowers per stem, *Linaria gracilis* produces 1 to 13 (up to 30) flowers (Flora of North America Editorial Committee, 2019).

Furthermore, while the lower lip of *Linaria japonica* is clearly white in the center, *Linaria japonica* remains blue, although it is slightly whitish.

When you actually look at the photos, you'll find that the differences are much bigger than you might have thought.

How is it pollinated? Despite its showy flowers, it seems to be entirely self-pollinating!?

How do *Linaria japonica* and *Linaria japonica* get pollinated?

The blue, mask-like flowers of the Linaria genus, though small, are striking in appearance, so one might assume they are insect-pollinated and reproduce through cross-pollination.

However, studies in the United States have shown that, contrary to appearances, all species of the genus Linaria are self-compatible and capable of self-pollination (pollination by pollen from the stamens of the same flower reaching the pistil), producing both cleistogamous and open flowers (Crawford, 2003; Crawford & Elisens, 2006).

Furthermore, cleistogamy occurs frequently, and many flowers complete self-pollination. Pollination occurs in closed flowers without any intervention, and in open flowers before they open.

Cleistogamous flowers are inconspicuous and rarely seen, but they are formed during the early and late stages of a plant's life cycle.

Therefore, despite being a very conspicuous flower, it is believed that most of them do not rely on insect pollination. This is a very surprising result.

The amount and composition of nectar are unknown, but nectar has not been observed in flowers cultivated in greenhouses or growing rooms.

There are a few insects that visit the open flowers; some observations indicate that honeybees and members of the family Carangidae visit them (Wolfe & Sellers, 1997), while others report that butterflies and possibly true bugs (Crawford, 2003).

Thus, because the genus Linaria incorporates only small amounts of other genes, it exhibits low genetic diversity, does not hybridize with other species, and significant population differentiation has been revealed through genetic studies. This is thought to be due to geographical isolation in North America (river, sea level rise, paleogeography).

It seems that this strong self-pollination strategy is related to the fact that the genus Linaria is able to thrive in urban areas of Japan.

By the way, why does it produce so many "seemingly useless flowers" like the open-flowered variety, even though it's entirely self-pollinating?

The study revealed that open flowers produce more seeds than cleistogamous flowers. This indicates that open flowers are more reproductively efficient than cleistogamous flowers, even without cross-pollination by insects.

In addition to this, it could be interpreted as a compromise that doesn't completely rule out the possibility of cross-pollination in case the environment changes.

How is the ivy-leaved toadflax pollinated?

On the other hand, what about the purple, mask-like flowers of the ivy-leaved toadflax?

In fact, research in France has shown that the same thing happens with *Linaria japonica*, with cleistogamous pollination occurring and self-pollination also taking place (Desaegher, 2017; Desaegher et al., 2017).

The exact ratio is unknown, but it is thought to be less extreme than in the genus Linaria, and is believed to involve a combination of cross-pollination and self-pollination.

However, it has been found that the flowers tend to be slightly smaller and the amount of pollen is lower in urban areas than in rural areas, and that the tendency for self-pollination is higher in urban areas of the ivy-leaved toadflax.

The specific pollinating insects found were small bees (such as Lasioglossum) accounting for 48.2%, bumblebees for 29.6%, and a small number of other large bees, honeybees, and syrphidae visiting the flowers.

Although these flowers are very similar, it can be said that the pollination tendencies of Linaria japonica and Linaria veitchii are different.

What are the seed dispersal methods?

The fruits of the genus Linaria are capsules, nearly spherical to oblong-ovate, with thin, hard walls that split open into 4-5 chambers when mature. The seeds are black, radially symmetrical, and prism-shaped with 4-7 corners.

It is believed that the genus Linaria primarily relies on gravity dispersal or wind dispersal (Crawford & Elisens, 2006).

The fruit of *Linaria japonica* is a capsule, spherical in shape with a diameter of 5-6 mm, hanging down by a long stalk, and splitting open when ripe. The seeds are less than 1 mm in diameter, black to brown in color, and have irregular wrinkles.

Toadflax is also treated as a form of gravity dispersal (Benvenuti et al., 2016).

References

Benvenuti, S., Malandrin, V., & Pardossi, A. (2016). Germination ecology of wild living walls for sustainable vertical gardens in urban environment. Scientia Horticulturae, 203, 185-191. https://doi.org/10.1016/j.scienta.2016.03.031

Crawford, PT (2003). Biosystematics of north American species of Nuttallanthus (Lamiales) [Doctoral dissertation, The University of Oklahoma]. https://www.proquest.com/openview/665d70305b3b2aa318f19aae12ba6adf/1?pq-origsite=gscholar&cbl=18750&diss=y

Crawford, PT, & Elisens, WJ (2006). Genetic variation and reproductive system among North American species of Nuttallanthus (Plantaginaceae). American Journal of Botany, 93 (4), 582-591. https://doi.org/10.3732/ajb.93.4.582

Desaegher, J. (2017). Urbanization effects on floral morphology and plant-pollinator relationships [Doctoral dissertation, Paris-Saclay University]. https://theses.hal.science/tel-01665328/

Desaegher, J., Nadot, S., Dajoz, I., & Colas, B. (2017). Buzz in Paris: flower production and plant–pollinator interactions in plants from contrasted urban and rural origins. Genetica, 145 (6), 513-523. https://doi.org/10.1007/s10709-017-9993-7

Flora of North America Editorial Committee (Eds.). (2019). Flora of North America (Vol. 17 Magnoliophyta: Tetrachondraceae to Orbobanchaceae). Oxford University Press. ISBN: 9780190868512, https://floranorthamerica.org/Main_Page

Kanagawa Prefecture Flora Survey Association. (2018). Kanagawa Prefecture Flora 2018 Electronic Edition. Kanagawa Prefecture Flora Survey Association. ISBN: 9784991053726,https://flora-kanagawa2.sakura.ne.jp/efloraofkanagawa.html

RBG Kew. (2026). The International Plant Names Index and World Checklist of Vascular Plants. Plants of the World Online. http://www.ipni.org and https://powo.science.kew.org/

Wolfe, LM, & Sellers, SE (1997). Polymorphic floral traits in Linaria canadensis (Scrophulariaceae). American Midland Naturalist, 138 (1), 134-139. https://doi.org/10.2307/2426661

Shimizu, K., Morita, H., & Hirota, S. (2001). Illustrated Guide to Naturalized Plants of Japan: 600 Species of Plant Invaders (Revised). National Rural Education Association. ISBN: 9784881370858

Akebia, Akebia trifoliata, Akebia quinata, and Stauntonia hexaphylla all belong to the Akebia family. They are climbing plants with palmately compound leaves, and a key characteristic is that male and female flowers bloom separately. Akebia and Akebia trifoliata are particularly famous for the edible white, gelatinous pulp inside their fruits. While they are associated with nostalgic rural flavors from childhood memories, few people may be able to distinguish between them. They can basically be distinguished by the shape of their leaves, and differences also appear in the shape of their flowers and the degree to which their fruits dehisce. Cross-pollination by insects is essential for their flowers, and it is known that the size difference between male and female flowers is a strategic feature. Seed dispersal is also interesting, as they rely on a variety of animals, including mammals, birds, and ants. This article will explain the classification, morphology, and ecology of the Akebia family.

What are Akebia, Mitsuba Akebia, Goyou Akebia, and Mube?

Akebia quinata, also known as Akebia quinata, is a deciduous climbing woody plant commonly found in the forest edges of hills and mountains, distributed across Honshu, Shikoku, and Kyushu in Japan; the Korean Peninsula; and China. Its Japanese name is said to derive from the fact that its fruit splits open.

Akebia trifoliata subsp. trifoliata, also known as three-leaved akebia, is a deciduous climbing woody plant commonly found in Hokkaido, Honshu, Shikoku, and Kyushu in Japan, as well as in China, growing at the edges of forests in hilly and mountainous areas.

Akebia x pentaphylla, also known as five-leaved akebia, is a natural hybrid of Akebia quinata and Akebia trifoliata, and is a deciduous climbing woody plant that is rarely found in areas where Akebia quinata and Akebia trifoliata grow together.

Stauntonia hexaphylla, also known as Tokiwaakebi, is a deciduous climbing woody plant distributed in Honshu (south of the Kanto region), Shikoku, Kyushu, and the Ryukyu Islands in Japan; the Korean Peninsula; and China. It grows in forest edges and is often planted as a hedge in parks and private homes. Makino suggests that the origin of the Japanese name comes from the fact that its fruit was offered to the imperial court, hence the name Ohonihe (大供) became Ohomube (苞苴), and then Mube (Kato and Nakamura, 1971). However, the basis for this argument is unclear.

All of these plants belong to the Akebia family, are climbing plants, have palmately compound leaves, and are monoecious, but a key characteristic is that their flowers are unisexual, meaning that male flowers grow separately.

[Seed Plant Encyclopedia #121] What are the species of the Akebia family? Photo list

The Lardizabalaceae family consists mainly of climbing woody plants, with shrubs being rare. The leaves are trifoliate or palmately compound with five leaflets. The flowers are unisexual, monoecious, and borne in racemes, radially symmetrical and trimeral. The sepals are petal-like. The fruit is an ellipsoidal berry with a fleshy pericarp. (Eastern Asia…)

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Of the four species, three, excluding Stauntonia hexaphylla, belong to the genus Akebia. Their most distinctive feature is that when ripe, their fruit splits open, exposing a liquid, fleshy interior.

This fruit is unique, and its name varies depending on the source. Although it is a "follicle (a fruit consisting of one carpel that dehisces along the internal or external suture)" (Shimizu, 2001), it is sometimes called a "berry" because its interior is a liquid that animals can eat (Mogi et al., 2000). Since 3 to 5 fruits can sometimes be clustered together, in this case it is called an "aggregate fruit," and is sometimes referred to as an "aggregate follicle" or "aggregate berry."

In Japan, there has been a long-standing tradition of eating this fruit, and it is associated with people's memories of the taste of the countryside from their childhood. There are also cultivated varieties of Akebia trifoliata, which are sometimes sold commercially.

However, several closely related species are known, and all of them are edible, so perhaps few people can correctly distinguish between them.

In particular, Akebia trifoliata has compound leaves with five leaflets, but Akebia quinata also has five leaflets, which can be confusing. Some companies even sell Akebia quinata as "Akebia trifoliata with five leaflets."

What are the differences between Akebia, Mitsuba Akebia, Goyou Akebia, and Mube?

As a fundamental point, Akebia quinata, Akebia trifoliata, and Akebia quinata belong to the Akebia genus, while Stauntonia hexaphylla belongs to the Stauntonia genus (Kanagawa Prefecture Flora Survey Association, 2018).

Therefore, there is a significant difference in form.

In Akebia, Akebia trifoliata, and Akebia quinata, the leaves are deciduous, the sepals are three cup-shaped, the stamens are six and free, and the fruit dehisces, whereas in Stauntonia hexaphylla, it is evergreen, the sepals are six in number (three outer ones are lanceolate and three inner ones are linear), the stamens are six and fused, and the fruit does not dehisce.

While there are many factors to consider, the biggest difference is whether the plant is deciduous or evergreen. In other words, Akebia, Akebia trifoliata, and Akebia quinata lose their leaves in winter, resulting in soft, thin, light green leaves, while Stauntonia hexaphylla retains its leaves even in winter, giving it sturdy, hard, dark green leaves. This can be observed by examining the leaves.

Another easily noticeable difference, even just looking at the leaves, is that in Stauntonia hexaphylla, the veins are prominent on both the upper and lower surfaces of the leaves, and the number of leaflets can range from three in young trees to five to seven in mature trees. These features are entirely unique to Stauntonia hexaphylla and are not found in the Akebia genus.

It's easy to mistakenly think that Akebia plants have multiple leaves, but these are palmate compound leaves, meaning that what was originally a single leaf has divided into 3 to 7 leaflets. These divided parts that look like a single leaf are called "leaflets."

Another point to note is that while botanical guides state that the fruit of Stauntonia hexaphylla does not split open, actual photographs show that it does split open slightly, though not as much as in the Akebia genus.

Of the remaining three species, Akebia trifoliata is a hybrid of Akebia quinata and Akebia quinata, and therefore exhibits intermediate characteristics (Kanagawa Prefecture Flora Survey Association, 2018; Yoshizawa and Arase, 2024; Hayashi, 2025).

Focusing on the number of leaflets, Akebia and Akebia trifoliata usually have five leaflets, while Akebia quinata has only three. This difference is reflected in its Japanese name.

However, since Akebia quinata can occasionally have 3 to 4 leaflets, you need to check for multiple leaflets.

If we focus on the serrations of the leaflets, we can see that while Akebia trifoliata and Akebia quinata usually have serrations, Akebia quinata does not.

However, this is also Akebia quinata, and some of the current year's branches in the upper layers lack serrations, so it is necessary to check multiple leaves.

Focusing on the flowers, in Akebia quinata, the male flowers are sparsely arranged and the sepals are pale purple, while the female flowers have long stalks and protrude from the male inflorescence. In contrast, in Akebia trifoliata and Akebia quinata, the male flowers are densely arranged and the sepals are dark reddish-purple, while the female flowers have somewhat shorter stalks and do not protrude from the male inflorescence.

Based on the above, I believe you can definitely distinguish between the four types.

What are the differences in how Akebia, Mitsuba Akebia, Goyou Akebia, and Mube are used?

The main use of Akebia and Mitsuba Akebia is, of course, for their sweet fruit. The fruit ripens in the autumn (around September to October).

In addition to consuming the wild fruit, there are also cultivated varieties of Akebia trifoliata for fruit production (Matsumoto et al, 2022; Yoshizawa & Arase, 2024).

The fruit consists of a pericarp and a white pulp (placenta) that encloses the black seeds, and this pulp is edible (Fruit Tree Horticulture Laboratory, Faculty of Agriculture, Yamagata University, 2020).

The typical way to eat it is to pick the fruit, eat the white gelatinous substance (placenta) as is, taste the flesh, and then spit out the seeds inside.

In rural areas, it has long been a popular snack for children playing in the mountains, and it is sometimes described as a "rare fruit that evokes nostalgia," adding color to fond childhood memories (Yoshizawa & Arase, 2024).

The fruit is sweet and juicy, and rich in nutrients such as sugars, proteins, amino acids, vitamins, and minerals (Huang et al., 2022).

Grapes are highly regarded nutritionally, containing a high amount of various vitamins such as beta-carotene, vitamin B, and vitamin C (108-930 mg/100 g), which is higher than apples, grapes, and bananas. They are also rich in minerals such as potassium (3.2-4.9 mg/g), magnesium (1.00-1.51 mg/g), and calcium (0.47-0.49 mg/g), as well as amino acids, including all eight essential amino acids.

The peel became a topic of discussion when YouTuber Hikakin, not knowing how to eat it, discarded the flesh and ate the peel raw, describing it as bitter and unpleasant (J-CAST News Entertainment Team, 2025). However, it is not edible raw.

However, the peel can also be eaten after being boiled or stir-fried, and dishes such as "stir-fried akebi peel with miso" are known (Fruit Tree Horticulture Laboratory, Faculty of Agriculture, Yamagata University, 2020).

The young shoots can be used in dishes such as blanched greens, salads, soups, and stir-fries (Takahashi, 2003). In the Tohoku region, the young shoots of Akebia trifoliata are called "kinome" (tree buds) because they contain less bitterness than Akebia quinata, and were used in "kinome-meshi" (tree bud rice).

In addition to being cultivated for ornamental purposes in horticulture (Huang et al., 2022), the outer bark of the thick vine stems is removed and sun-dried, and this is called "Mokutsu," which has been used as a herbal medicine effective against nephritis, urethritis, and cystitis due to its diuretic, anti-inflammatory, analgesic, cardiac stimulant, antibacterial, and antioxidant properties (Maciąg et al., 2021).

Akebia quinata does not produce fruit, so it is not used for food.

While the fruit of the Stauntonia hexaphylla is edible, it is small and does not split open completely, making it difficult to eat, and therefore it is rarely found in the market.

However, Makino suggests that the origin of the Japanese name is that the fruit was offered to the imperial court, and that this was called "Ōhonihe" (大供), which became "Ōmube" (苞苴), and then "Mube" (Kato and Nakamura, 1971). There is also a theory that when Emperor Tenji was presented with it, he replied, "Mube naru kana" (meaning "That is indeed true"). The veracity of these claims is quite questionable, but it seems certain that Mube was used in ancient times (Wano, 2015).

How did pollination work? Was it to deceive insects with large female flowers?!

The shape of the flowers differs greatly between the Akebia and Stauntonia genera (Kanagawa Prefecture Flora Survey Association, 2018).

In the Akebia genus, the flowering period is in spring, from April to May. Male flowers are numerous and borne at the tip of the inflorescence, with short filaments that curve inward in an arching shape, forming a spherical cluster. Female flowers are larger than male flowers, borne in small numbers at the base of the inflorescence, and have 3 to 9 oblong carpels that spread outwards. What appear to be three petals are actually modified sepals.

It has a strong scent and is sometimes called "the flower with the fragrance of chocolate" in Europe and America.

What kinds of insects visit this flower? Akebia species are self-compatible and cannot produce fruit without pollen from other individuals.

Studies on Akebia have shown that the main pollinating insects are small, solitary wasps (non-caste wasps) such as Lasioglossum sp., hoverflies Epistrophe balteata (Syrphidae), and Japanese honeybees Apis cerana japonica (Apidae) (Kawagoe & Suzuki, 2002).

While there is insufficient research on Akebia trifoliata, some believe it may be similar to Akebia quinata (Matsumoto et al, 2022). However, there are morphological differences, such as the male flowers of Akebia trifoliata being darker in color, so it has not been verified whether they are truly the same.

While the Japanese akebia (Akebia quinata) produces flowers, it does not produce fruit, so it cannot reproduce.

By the way, there's a curious difference between the male and female flowers of the Akebia genus. The female flowers are noticeably larger and more conspicuous than the male flowers. Why is this?

This is thought to be "intersexual mimicry," where female flowers mimic male flowers (Kawagoe & Suzuki, 2002; 2003). In other words, since female flowers have no stamens, they naturally have no pollen and offer no reward to pollinators, but they grow larger than male flowers to appear more attractive to pollinators in order to deceive insects into thinking "there's food here!"

Furthermore, especially in solitary bees, they will visit the more attractive-looking female flowers before moving on to the male flowers. This prevents self-pollination within the same individual by preventing pollen from the male flowers from touching the stigma of the female flowers, thus promoting cross-pollination.

As mentioned above, Akebia is self-incompatible, so this cross-pollination is thought to be for the purpose of avoiding reproductive interference (by its own pollen), rather than suppressing inbreeding (preventing inbreeding depression) (Kawagoe & Suzuki, 2005).

Surprisingly, however, hoverflies can distinguish between male and female flowers and only visit the male flowers, resulting in a situation where they steal nectar.

On the other hand, Stauntonia hexaphylla flowers in spring, from April to May, producing short racemes from the leaf axils. These inflorescences have 6 sepals and bear 3 to 7 pale yellow flowers that face downwards and have a single reddish-purple stripe on the inside (Mogi et al., 2000). There are no significant differences between male and female flowers except for the stamens and pistils.

Despite having the exact same flowering period, the reason why the male and female Stauntonia hexaphylla are identical in appearance remains unknown, unfortunately due to insufficient research on pollinating insects.

The facts above confirm that wild insects (mainly bees) produce delicious akebi fruit, both wild and cultivated. This kind of benefit is called an "ecosystem service," so if you want to eat delicious akebi, please take an interest not only in the akebi itself, but also in the natural environment that supports these insects.

How did they disperse their seeds? They used all sorts of methods: mammals, birds, ants, you name it!?

As mentioned above, the fruits of the Akebia family ripen in the autumn and are "follicles" that split open or crack, but are also called "berries" because the inside is a liquid that animals can eat.

The thick rind changes from green to red to purple as it ripens, and when it splits open, the inside is exposed, revealing black seeds encased in a white, gelatinous placenta.

Fruits that are clearly large and would be considered tasty for humans are likely to be dispersed by animal means, particularly by mammals.

In fact, the fruit of Akebia has been used by martens and raccoons (Takatsuki, 2017; 2018), and there are records of the fruit of Akebia trifoliata being used by martens, raccoons, and Japanese macaques (Takatsuki, 2017; Kumagai and Saito, 2022; Otani, 2005).

The fruits of the Stauntonia hexaphylla are also used by martens and raccoons (Takatsuki, 2017; 2019).

The slimy seed coat is thought to be adapted to slip through the teeth of animals (Okamoto, 1999).

However, there are also records of an increase in seedlings of Akebia quinata and Akebia trifoliata within goldenrod communities (Karasawa, 1978). This suggests that birds may be contributing to seed dispersal of Akebia quinata and Akebia trifoliata.

Generally, red fruits are only visible to birds and monkeys with well-developed color vision, so considering this point, it is plausible that seeds are dispersed by both mammals and birds.

Furthermore, the seeds of Akebia and Akebia trifoliata have elaiosomes. This indicates that these are parts that ants eat, and that after being eaten by animals, the seeds are excreted in their feces and then dispersed again by ants, thus contributing to ant dispersal (Nakanishi, 1988).

In the field, there have been observations of brown ants gathering around the seeds (Kusui & Kusui, 1999). In experiments where seeds were placed directly near ant nests, black garden ants and brown ants carried them away (Fujii et al., 2012).

However, unlike Akebia quinata and Akebia trifoliata, Stauntonia hexaphylla does not have elaiosomes (Kusui & Kusui, 1999).

References

Huang, P., Zang, F., Li, C., Lin, F., Zang, D., Li, B., & Zheng, Y. (2022). The Akebia genus as a novel forest crop: A review of its genetic resources, nutritional components, biosynthesis, and biological studies. Frontiers in Plant Science, 13, 936571. https://doi.org/10.3389/fpls.2022.936571

Fujii, Mari; Kosaka, Ayumi; and Masui, Keiji. (2012). Plants that rely on ants to disperse their seeds. Kyosei no Hiroba, 7, 63-68. ISSN: 1881-2147, https://www.hitohaku.jp/publication/book/kyousei7_063.pdf

J-Cast News Editorial Department, Entertainment Team. (February 6, 2025). Hikakin, who caused a controversy 8 and a half years ago, immediately apologizes... and looks back on it with laughter: "Why did I have to apologize...?" He reveals his true feelings. J-Cast News. https://www.j-cast.com/2025/02/06501301.html

Karasawa, Koichi. (1978). A study on the diet and seed dispersal of fruit-eating birds in urban areas. Birds, 27 (1), 1-20. https://doi.org/10.3838/jjo1915.27.1

Kanagawa Prefecture Flora Survey Association. (2018). Kanagawa Prefecture Flora 2018 Electronic Edition. Kanagawa Prefecture Flora Survey Association. ISBN: 9784991053726

Kato, Kaname & Nakamura, Tsuneo. (1971). Yama-kei Color Guide: Flowering Trees 1. Yama-kei Publishers.

Kawagoe, T., & Suzuki, N. (2002). Floral sexual dimorphism and flower choice by pollinators in a nectarless monoecious vine Akebia quinata (Lardizabalaceae). Ecological Research, 17 (3), 295-303. https://doi.org/10.1046/j.1440-1703.2002.00489.x

Kawagoe, T., & Suzuki, N. (2003). Flower-size dimorphism avoids geitonogamous pollination in a nectarless monoecious plant Akebia quinata. International Journal of Plant Sciences, 164 (6), 893-897. https://doi.org/10.1086/378659

Kawagoe, T., & Suzuki, N. (2005). Self-pollen on a stigma interferes with outcrossed seed production in a self-incompatible monoecious plant, Akebia quinata (Lardizabalaceae). Functional Ecology, 19 (1), 49-54. https://doi.org/10.1111/j.0269-8463.2005.00950.x

Hayashi, Masayuki. (2025). Tree Leaves, 3rd Edition: Identifying 1390 Species Through Real-Life Scans. Yama-kei Publishers. ISBN: 9784635070447

Kumagai, Minami and Saito, Masayuki. (2022). Seasonal changes in the diet of raccoons in temperate forests of the Shonai region of Yamagata Prefecture. Journal of the Tohoku Forest Science Society, 27 (1), 1-10. https://doi.org/10.18982/tjfs.27.1_1

Kusui, Haruo & Kusui, Yoko. (1999). Tree seeds of temperate forests carried by martens. In Keisuke Ueda (Ed.), Seed Dispersal: The Evolution of Mutual Aid Vol. 2: Forests Created by Animals (pp. 37-50). Tsukiji Shokan. ISBN: 9784806711933

Nakanishi, Hiroki. (1988). Ant-dispersed plants distributed in the warm temperate zone of Japan. Journal of the Ecological Society of Japan, 38 (2), 169-176. https://doi.org/10.18960/seitai.38.2_169

Maciąg, D., Dobrowolska, E., Sharafan, M., Ekiert, H., Tomczyk, M., & Szopa, A. (2021). Akebia quinata and Akebia trifoliata: a review of phytochemical composition, ethnopharmacological approaches and biological studies. Journal of Ethnopharmacology, 280, 114486. https://doi.org/10.1016/j.jep.2021.114486

Matsumoto, D., Shimizu, S., Shimazaki, A., Ito, K., & Taira, S. (2022). Effects of self-pollen contamination in artificial pollination on fruit set of 'Fuji Murasaki' Akebia trifoliata. The Horticulture Journal 91 (4), 431-436. https://doi.org/10.2503/hortj.UTD-385

Mogi, Toru; Ota, Kazuo; Katsuyama, Teruo; Takahashi, Hideo; Shirokawa, Shiro; Yoshiyama, Hiroshi; Ishii, Hidemi; Sakio, Hitoshi; and Nakagawa, Shigetoshi. (2000). Flowers Blooming on Trees: Polypetalous Flowers (Vol. 2, 2nd edition). Yama-kei Publishers. 719pp. ISBN: 9784635070041

Okamoto, Motoharu. (1999). The mutually beneficial relationship between birds and succulents. In Keisuke Ueda (Ed.), Seed Dispersal: The Evolution of Mutual Aid Vol. 1: Seeds Carried by Birds (pp. 27-39). Tsukiji Shokan. ISBN: 9784806711926

Otani, T. (2005). Characteristics of medium-sized mammals as seed dispersers of berries—mainly using Japanese macaques as an example. Nagoya University Journal of Forest Science, 24, 7-43. https://doi.org/10.18999/nagufs.24.7

Shimizu, Takemi. (2001). Illustrated Dictionary of Botanical Terms. Yasaka Shobo. ISBN: 9784896944792

Takahashi, Hideo. (2003). Wild Edible Plants of Japan. Gakken Plus. ISBN: 9784054018815

Takatsuki, Shigeki. (2017). Characteristics of fruits used by martens—a review. Mammalian Science, 57 (2), 337-347. https://doi.org/10.11238/mammalianscience.57.337

Takatsuki, Shigeki. (2018). Characteristics of fruits used by raccoons—a review. Mammalian Science, 58 (2), 237-246. https://doi.org/10.11238/mammalianscience.58.237

Wano, Yasuhiro. (2015, November 16). The "Akebia" Fruit of Immortality: People from all over Japan constantly seek this legendary fruit that has been offered to the Imperial Family since ancient times... Sankei News. https://www.sankei.com/article/20151116-R4UEWT34HRNKDMX4RQHNCLPSM4/

Yamagata University, Faculty of Agriculture, Department of Fruit Tree Horticulture. (2020). The Story of Yamagata's Akebi. Sugihado Printing. ISBN: 9784991178504, https://ssl.samidare.jp/~lavo/zaisakuken/box/akebi.pdf

Yoshizawa, Yuri & Arase, Teruo. (2024). Taxonomic study of three Akebia species based on morphological variation of leaves. Shinshu University Faculty of Agriculture AFC Reports, 22, 45-54. ISSN: 2433-8877, http://hdl.handle.net/10091/0002002080

Hydrocotyle sibthorpioides, Hydrocotyle japonica, Hydrocotyle umbellata, and Hydrocotyle kobus are all members of the Hydrocotyle genus in the Araliaceae family. They are perennial herbs that creep along the ground in slightly shaded areas from mid-to-forests to woodlands, and are notable for their very small, nearly orbicular simple leaves. However, their flowers and fruits are small and inconspicuous, so they are often overlooked and relatively difficult to distinguish. However, they can generally be distinguished by checking the amount of hair on the upper and lower surfaces of the leaves and the degree of leaf lobes. The insects that visit the flowers are not well studied, and while flies and ants are strong candidates, they are not yet known. This article will explain the classification, morphology, and ecology of the Hydrocotyle genus.

What are *Hydrocotyle japonica*, *Hydrocotyle sibthorpioides*, *Hydrocotyle japonica*, and *Hydrocotyle sibthorpioides*?

Hydrocotyle sibthorpioides, also known as "blood-stopping grass," is a perennial herb that is very common and grows along roadsides and in gardens, distributed in Honshu, Shikoku, Kyushu, the Ryukyu Islands, and the Ogasawara Islands of Japan; the southern Korean Peninsula; Taiwan; China; Vietnam; Budan; India; Nepal; and Africa (Kanagawa Prefecture Flora Survey Association, 2018).

Hydrocotyle yabei var. yabei, also known as Himechidome (small blood-stopping grass), is a perennial herb that is distributed in Hokkaido (Oshima Subprefecture), Honshu, Shikoku, and Kyushu in Japan, as well as Jeju Island (South Korea), and is fairly common in the forest floor from hilly to mountainous areas.

Hydrocotyle maritima, also known as Nohidome (wild blood stopper), is a perennial herb commonly found in forest edges, field edges, and wetlands, distributed across Honshu, Shikoku, Kyushu, the Ryukyu Islands, and the Ogasawara Islands in Japan; the Korean Peninsula; and China.

Hydrocotyle ramiflora, also known as "large hemostatic flower," is a perennial herb commonly found in grasslands, lawns, and field edges in Japan (Hokkaido, Honshu, Shikoku, and Kyushu) and the Korean Peninsula.

Both belong to the genus Hydrocotyle in the family Araliaceae. They are perennial herbs that creep along the ground in slightly shaded areas from urban areas to forests, and are notable for their very small, almost orbicular, simple leaves. They also have the characteristic of having two schizocarps.

The Japanese name "Chido-megusa" comes from the fact that applying the juice of crushed leaves to small wounds stops bleeding, and I-sesamin is considered to be an active ingredient (Osawa, 1999). It has also been traditionally used medicinally for infectious diseases around the world, and scientific evidence is being proven to support this (Hazarika et al., 2021).

However, because they are so inconspicuous, they are often overlooked, and their flowers and fruits are also plain, making them very difficult to distinguish at a glance.

What are the differences between *Hydrocotyle japonica*, *Hydrocotyle sibthorpioides*, *Hydrocotyle japonica*, and *Hydrocotyle sibthorpioides*?

While the four species can be distinguished to some extent by knowing the shape of their leaves, more accurate identification is possible by recording both the upper (surface) and lower (back) surfaces of the leaves (Kanagawa Prefecture Flora Survey Association, 2018).

First, in *Hydrocotyle japonica* and *Hydrocotyle sibthorpioides*, the entire stem creeps along the ground and the leaf blades are thin and hairless on both sides, whereas in *Hydrocotyle japonica* and *Hydrocotyle sibthorpioides*, the tip of the stem grows obliquely upward and the leaf blades are thick and hairy on both sides or the underside.

Regarding *Hydrocotyle japonica* and *Hydrocotyle sibthorpioides*, *Hydrocotyle japonica* has shallowly lobed leaf margins, somewhat rounded serrations, about a dozen flowers, and a truncate fruit base, while *Hydrocotyle sibthorpioides* has deeply lobed leaf margins, nearly triangular serrations, fewer than 10 flowers, and a heart-shaped fruit base.

Regarding *Hydrangea macrophylla* and *Hydrangea serrata*, *Hydrangea macrophylla* has deeply lobed leaf margins, a nearly pentagonal outline, hairy veins on the upper surface of the leaf, and a petiole longer than its corresponding pedicel, while *Hydrangea serrata* has very shallowly lobed leaf margins, a nearly circular outline, a hairless upper surface of the leaf, and a petiole shorter than its corresponding pedicel.

There are various factors to consider, but ultimately, focusing on the hairs and incisions of the leaf blade should suffice. The hairs on the leaves of the Hydrocotyle genus are erect and clearly visible in photographs.

Generally speaking, it's worth noting that *Cydonia oblonga* is often found in urban areas, while the other three species are found in areas with a relatively high degree of naturalness.

Are there any other similar species?

There is a form of *Hydrangea macrophylla* with large leaf blades and a narrow base, which is sometimes classified as *Hydrangea macrophylla var. japonica*, but some believe that the leaf shapes are continuous and difficult to distinguish (Kanagawa Prefecture Flora Survey Association, 2018).

Among the native species, there is also a species called Hydrocotyle javanica, but it can be easily distinguished by its unique characteristic of having short, curled hairs all over the flower stalks and leaf stalks, which is not seen in other species.

The genus Hydrocotyle includes several species that have attracted attention worldwide as invasive species that have escaped the trade and become naturalized.

Hydrocotyle verticillata var. triradiata, also known as water mushroom or water coin, is a plant that has escaped cultivation in aquariums and become naturalized. It can be easily distinguished by its nearly circular leaf blade and the shield-shaped petiole attached to the center of the leaf blade.

The Brazilian pennywort, Hydrocotyle ranunculoides, a designated invasive alien species, grows in water and can be easily distinguished by its succulent flesh and thick petioles.

How does pollination occur? What insects visit very small flowers?

It is unclear whether this is true for all species of the genus Hydrocotyle, but in introduced species such as Hydrocotyle brevifolia and Hydrocotyle sibiricum, vegetative reproduction is mainly carried out by stolons (Nakajima and Oki, 2017).

However, some species reproduce sexually through cross-pollination in order to incorporate genes from other individuals and become more resilient to environmental changes.

The genus Hydrocotyle blooms from June to October, producing one to several single umbels. The flowers are very small, about 2 mm in diameter, and typically consist of 5 petals, 5 stamens, and 2 pistils.

While there is a lack of research on the pollination methods of the genus Hydrocotyle, one study, based on observations, literature, and flower morphology, treats it as being pollinated by flies, along with the genus Stilbocarpa (Garcia et al., 2022).

Indeed, the very small flowers of the Hydrocotyle genus could be preyed upon by small fly-like insects.

Records for individual species are even more scarce.

There are records of the hoverfly Paragus jozanus and the bee species Lasioglossum sp. visiting the flowers of Hydrangea macrophylla (Yamazaki & Kato, 2003).

There are records of ants and thrips visiting the flowers of *Hydrocotyle sibiricum* (Ushijima & Ushijima, 2014).

Although insects occasionally visit the flowers of *Polytrichum commune*, self-pollination is considered to be the primary method of pollination (Ruhsam et al., 2025).

While I'm unsure about other species, I've also observed ants visiting the flowers of the Japanese honeysuckle.

Ants are generally thought to contribute very little to cross-pollination, and there are two reasons for this.

Firstly, ants tend to visit only the same flowers or flowers from the same plant, and feed only on nectar. Therefore, they are often considered to have no contribution to pollination, or if they do, it is only self-pollination or neighboring flower pollination, and they do not contribute to cross-pollination (Rostás et al., 2018). Even when self-pollination or neighboring flower pollination occurs, the subsequent seed germination rate and seedling mortality rate may be high.

Furthermore, it has been found that the secretions from the metapleural gland, which ants release to protect themselves from microbial infections, are also effective against pollen, reducing its germination rate (Dutton & Frederickson, 2012).

However, since ants contribute to pollination in species that are self-compatible and capable of self-pollination (de Vega & Gómez, 2014), and since species of the genus Hydrocotyle are known to be self-compatible and for which self-pollination is the primary pollination strategy (Nery, 2019), I am paying close attention to the possibility that ants contribute to pollination in the genus Hydrocotyle.

What are the seed dispersal methods?

There appears to be no comprehensive study on the seed dispersal methods of the genus Hydrocotyle, but one study treats Hydrocotyle sibthorpioides and Hydrocotyle macrophylla as simply dispersing by gravity (Nishida et al., 1993).

On the other hand, since water-flow dispersal is also used for invasive species such as Brazilian pennywort and prickly pear (Nakajima and Oki, 2017), it is possible that similar methods exist for native species as well.

References

de Vega, C., & Gómez, JM (2014).

Dutton, EM, & Frederickson, ME (2012). Why ant pollination is rare: new evidence and implications of the antibiotic hypothesis. Arthropod-Plant Interactions, 6 (4), 561-569. https://doi.org/10.1007/s11829-012-9201-8

Garcia, JE, Hannah, L., Shrestha, M., Burd, M., & Dyer, AG (2022). Fly pollination drives convergence of flower coloration. New Phytologist, 233 (1), 52-61. https://doi.org/10.1111/nph.17696

Hazarika, I., Mukundan, GK, Sundari, PS, & Laloo, D. (2021). Journey of Hydrocotyle sibthorpioides Lam.: From traditional utilization to modern therapeutics—A review. Phytotherapy Research, 35 (4), 1847-1871. https://doi.org/10.1002/ptr.6924

Kanagawa Prefecture Flora Survey Association. (2018). Kanagawa Prefecture Flora 2018 Electronic Edition. Kanagawa Prefecture Flora Survey Association. ISBN: 9784991053726

Nakajima, Yoshitaka & Oki, Yoko. (2017). Comparison of cold tolerance and seed reproduction characteristics of three species of the genus Hydrocotyle, an introduced aquatic plant. Weed Research, 62 (2), 19-24. https://doi.org/10.3719/weed.62.19

Nery, EK (2019). An integrated taxonomic approach to the Hydrocotyle stella Pohl ex DC.(Araliaceae) complex from the brazilian atlantic forest [Master's thesis, Federal University of Santa Catarina]. https://repositorio.ufsc.br/handle/123456789/211445

Nishida, Tomoko; Harashima, Tokuichi; and Sato, Kenji. (1993). Weed growth in pastures with different uses. Research Report of the Grassland Research Station, 47, 45-54. https://agriknowledge.affrc.go.jp/RN/2010490600

Osawa, Toshihiko. (1999). Functional properties of lignans. Journal of the Japan Oil and Lime Chemical Society, 48 (10), 1041-1048. https://doi.org/10.5650/jos1996.48.1041

Rostás, M., Bollmann, F., Saville, D., & Riedel, M. (2018). Ants contribute to pollination but not to reproduction in a rare calcareous grassland forb. PeerJ, 6, e4369. https://doi.org/10.7717/peerj.4369

Ruhsam, M., Hollingsworth, PM, & Darwin Tree of Life Consortium. (2025). The genome sequence of the Marsh Pennywort, Hydrocotyle vulgaris L. (Apiales: Araliaceae). Wellcome Open Research, 10, 370. https://doi.org/10.12688/wellcomeopenres.24582.1

Ushijima, Kiyoharu & Ushijima, Tomiko. (2014). Flowering morphology of Hydrangea macrophylla. Kyousei no Hiroba, 9, 63-66. ISSN: 1881-2147, https://www.hitohaku.jp/publication/book/kyousei9_p63-66.pdf

Yamazaki, K., & Kato, M. (2003). Flowering phenology and anthophilous insect community in a grassland ecosystem at Mt. Yufu, western Japan. Contributions from the Biological Laboratory, Kyoto University, 29, 255-318. http://hdl.handle.net/2433/156407

Japanese yam (Dioscorea japonica), Chinese yam (Dioscorea longa), Japanese yam (Dioscorea tokoro), and bitter yam (Dioscorea japonica) all belong to the genus Dioscorea in the family Dioscoreaceae. They produce edible tubers and bulbils and are very common climbing perennial plants often seen in urban areas. The genus Dioscorea, also known as yam, is a vast group containing many species, but these four species are the most common in Japan. However, they are often confused, especially Japanese yam (Dioscorea japonica ) and Chinese yam (Dioscorea longa), which are used to make "tororo" (grated yam), and this confusion has even occurred at the government level. While there are other species besides these four, these four can be distinguished by the shape of their leaves and flowers, and the presence or absence of tubers (rhizomes) and bulbils. Their reproductive strategies are extremely diverse; tubers, bulbils, flowers, and fruits are all involved in reproduction, but how they are used differs greatly from species to species. Therefore, although they are often confused, each species has a strong biological individuality. This article will explain the classification, morphology, and ecology of the genus Dioscorea.

What are Japanese yam, Chinese yam, Japanese nightshade, and bitter yam?

Japanese yam (Dioscorea japonica), also known as yamaimo or jinenjo, is a climbing perennial herb distributed in the temperate to subtropical regions of Honshu, Shikoku, Kyushu, and the Ryukyu Islands in Japan, as well as the Korean Peninsula, China, and Taiwan. It commonly grows in alluvial plains and mountainous areas, along forest edges, roadsides, field edges, vacant lots, and park planting areas. However, since only the underground rhizome (edible part) is annual, the leaves above ground wither in winter.

Nagaimo (Japanese yam), also known as Dioscorea polystachya, is a climbing perennial herb distributed in the temperate to subtropical regions of Honshu, Shikoku, Kyushu, and the Ryukyu Islands in Japan; the Korean Peninsula; China; and Taiwan. It grows in alluvial plains and hillsides of the Castanopsis and Quercus zones, along forest edges, fields, vacant lots, and park planting areas. However, since only the underground rhizome (edible part) is annual, the leaves above ground wither in winter. There are various theories regarding the distribution of nagaimo in Japan; one theory suggests it may not be a native species, but rather was introduced from China and may have been cultivated in the late Jomon period, preceding grains and rice (Yoshida, 2019). Numerous cultivated varieties exist.

Dioscorea tokoro is a climbing perennial herb that is distributed in Hokkaido, Honshu, Shikoku, and Kyushu in Japan; as well as in the temperate to warm zones of the Korean Peninsula and China. It is very common to find it growing in alluvial plains and mountainous areas from the Castanopsis and Quercus zones to the Beech zone, including forest edges, grasslands, vacant lots, and planted areas in parks.

Dioscorea bulbifera, also known as space potato or air potato, is a climbing perennial herb widely distributed in Honshu, Shikoku, Kyushu, and the Ryukyu Islands of Japan; and in the subtropical to tropical regions of Asia and Oceania. It grows in forest edges and grasslands along rivers in alluvial plains and hilly areas of the Castanopsis and Quercus zones.

All of these belong to the genus Dioscorea in the family Dioscoreaceae, and are very common climbing perennial plants that can often be seen even in urban areas. The genus Dioscorea is a group that includes a vast number of species, but these four species are the most commonly encountered in Japan.

[Seed Plant Encyclopedia #058] What are the species of the Dioscoreaceae family? Photo list

The Dioscoreaceae family consists of herbaceous or climbing plants, comprising over 630 species across three genera distributed worldwide, primarily in tropical and subtropical regions. In Japan, only the genus *Dioscorea* is found. This article provides a comprehensive, field-guide-style introduction to plants of the Dioscoreaceae family. Basic information is available from the Kanagawa Prefectural Botanical Garden…

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Its most distinctive feature is that it can form roots or bulbils, commonly referred to as "potatoes." Of the four species, only Japanese yam (Dioscorea japonica) and Chinese yam (Dioscorea japonica) are edible in Japan.

The root of the nagaimo yam is eaten as "tororo" when grated, and it's an indispensable topping when you're eating out and paying a little extra for it, especially with soba noodles or rice bowls.

However, Japanese yam (Dioscorea japonica) and Chinese yam (Dioscorea japonica) are extremely often confused. They are so confused that, according to statistics from the Ministry of Agriculture, Forestry and Fisheries, they weren't even distinguished from each other until 2008. Few websites clearly explain the difference between them.

Furthermore, in the wild, Japanese yam (Dioscorea japonica) and Dioscorea tokoro often grow together, so it is necessary to distinguish between the two.

Furthermore, Japanese specimens of bitter cinnamon are bitter and not typically eaten, so it's necessary to distinguish them from other plants.

Although these groups are very similar, there are often situations where it is necessary to distinguish between them.

What are the differences between Japanese yam (Dioscorea japonica), Chinese yam (Dioscorea tokoro), and bitter yam (Dioscorea japonica)?

The genus Dioscorea is a very large group of known species, and it's difficult to describe all the differences here, but I'll focus on four relatively common species.

Regarding the leaves, there is a difference in that the leaves of Japanese yam (Dioscorea japonica) and Chinese yam (Dioscorea japonica) are triangular-ovate to triangular-lanceolate, while those of Japanese yam (Dioscorea tokoro) and bitter yam (Dioscorea japonica) are orbicular-cordate (heart-shaped).

However, since yams exhibit considerable variation, with some having leaves that are nearly heart-shaped, it is important to examine multiple leaves.

Regarding Japanese yam (Dioscorea japonica) and Chinese yam (Dioscorea japonica), the difference lies in the fact that in Japanese yam, the lateral base does not protrude in an ear-like shape and the base of the leaf blade is green, while in Chinese yam, the lateral base protrudes in an ear-like shape and the base of the leaf blade is reddish-purple.

Regarding Dioscorea tokoro and Dioscorea japonica, the difference is that in Dioscorea tokoro, the base of the petiole is smooth, while in Dioscorea japonica, the base of the petiole protrudes in a stipule-like manner and clasps almost half of the stem.

There are even greater differences in the presence or absence of rhizomes and bulbils, as well as in the shape of the flowers. Please check the details below.

What are the differences in how to use Japanese yam (Dioscorea japonica), Chinese yam (Dioscorea tokoro), and bitter yam (Dioscorea japonica)?

The four uses vary greatly depending on the developmental stage of the organs and the taste of each of the four types.

When used, yams are usually for food, and there are typically two types: the wild yam (Dioscorea japonica), which is common in the wild, and the cultivated Chinese yam (Dioscorea longa). There are various theories about the distribution of Chinese yams in Japan, and one theory suggests that it is questionable whether it is a native species, and that it may have been introduced from China and cultivated in the late Jomon period, preceding grains and rice (Yoshida, 2019). It already appears in the dictionary "Wamyō Ruijushō," which was compiled in the mid-Heian period, suggesting that it was already being used.

For a long time, the two species were rarely distinguished for consumption, and even in the Ministry of Agriculture, Forestry and Fisheries' crop survey statistics, they were not differentiated until 2008. However, since 2007, it has been found that the majority of what is sold as "yamaimo" (Japanese yam) is actually nagaimo (Chinese yam).

Both Japanese yam (Dioscorea japonica) and Chinese yam (Dioscorea japonica) have a single cylindrical, fleshy "root" (also known as a tuber, or "potato") underground. In Japan, the roots of both species are collectively called "tororo imo," and in the case of Japanese yam, they are also called "jinenjo." Chinese yam has a thicker shape.

However, cultivated varieties of Japanese yam, such as Tsukuneimo and Yamatoimo (Yamatoimo), are round in shape.

This part is cut into sticks and mixed with okra, or grated and mixed with white soy sauce and dashi to make the sticky "tororo," which is commonly eaten as "tororo soba," "tororo udon," or "mugitoro gohan." The stickiness is due to mucilage (or mucin, according to some papers), and it can be eaten raw.

It is said that grated yam (Yamaimo) is far stickier than grated Chinese yam (Nagaimo).

While cultivated nagaimo (Chinese yam) is typically used in restaurants, wild yam (Yamaimo) was likely also used before the Edo period, and even today, wild yam is sometimes used intentionally due to its different texture.

Furthermore, Japanese yam, Chinese yam, and bitter yam form "bulbils" in the leaf axils.

Mukago, also known as "bulbils," are the buds that have developed to contain nutrients for reproduction.

Because the bulbils of both Japanese yam and Chinese yam have a potato-like texture, they are eaten. They are cooked with rice to make "mukago rice," or served as a snack with drinks at izakayas (Japanese pubs), sometimes stir-fried with salt, or as "deep-fried mukago" or "mukago tempura." However, it is usually the Chinese yam that is eaten.

In addition, it was sometimes called wild yam or soil yam and used as a herbal medicine.

On the other hand, while bitter corn has rhizomes and bulbils, both are very bitter and are not usually eaten. This is as its Japanese name suggests. However, cultivated varieties are commonly eaten worldwide because the bitterness can be removed by boiling, and it is popular in West Africa. In Japan, it is sold under the names "space potato" or "air potato."

As for *Dioscorea tokoro*, it lacks both rhizomes and bulbils, so it is not usually eaten. However, it does form a rhizome instead of rhizomes.

Are there any other similar species?

The genus Dioscorea is a very broad group, so it's impossible to list them all here. However, some species that resemble Dioscorea tokoro found in the wild in Japan include Dioscorea japonica, Dioscorea japonica, Dioscorea tokoro, Dioscorea japonica, and Dioscorea japonica, so caution is advised.

Globally, edible yams of the genus Dioscorea are collectively called "yam," and include species such as Dioscorea alata and Dioscorea elephantipes (also known as Dioscorea elephantipes).

Yams are rich in dietary fiber, starch, sugars and other carbohydrates, as well as protein, lipids, vitamins, and minerals, providing approximately 200 calories per person per day to 300 million people in tropical regions, making them one of the world's most important staple root vegetables and tubers (Obidiegwu et al., 2020).

How do they reproduce? Why do they reproduce through bulbils and pollination?

Reproductive methods vary greatly depending on the species.

Japanese yam (Dioscorea japonica), Chinese yam (Dioscorea japonica), and bitter yam (Dioscorea japonica) reproduce asexually through clonal propagation via bulbils and sexually through insect-pollinated flowers, incorporating genes from other plants.

In the reproduction of bulbils, they are either dropped to the ground by gravity, washed away by water, or, like acorns, carried by mice and stored underground (stored), and then germinate when forgotten by the mice (Mizuki & Takahashi, 2009).

Compared to asexual reproduction via rhizomes, stolons, and stolons, bulbils are considered to have advantages in that they can move to spatially distant, suitable environments for growth and are resilient to disturbed areas (such as aquatic environments and roadsides where the environment changes drastically) (Inoue, 2007).

On the other hand, *Dioscorea tokoro* does not produce bulbils and reproduces only sexually through insect-pollinated flowers.

Why do Japanese yam, Chinese yam, and bitter yam reproduce in two different ways, including by adding bulbils?

Generally, two advantages are explained (Takahashi & Inoue, 2005; Mizuki & Takahashi, 2009).

The first advantage is that bulbils weigh about 100 times more than seeds in dry weight, and they can germinate and grow even in dark environments, so the survival rate of offspring is higher with bulbils than with seeds.

The second advantage is that organisms want to pass on all of their genes if possible, so creating bulbils, which are clones, allows twice as many of the female parent's genes to be passed on as seeds.

However, this might lead you to wonder why they reproduce sexually through insect pollination.

There are two potential advantages to this as well.

The first advantage of sexual reproduction is that, due to the effects of various genes, the offspring become more resistant to pests, diseases, pathogens, and changes in the natural environment.

The second feature is unique to the genus Dioscorea, which has capsules with "wings" that make it easier to catch the wind, and its seeds are also circular with thin wings around the edge. These features allow for efficient seed dispersal (wind dispersal), which has the advantage of sending the offspring further than bulbils, thus reducing the risk of competition among offspring (such as competing for nutrients).

While it is true that bulbils can be transported far from the mother plant by mice, it has been found that their range of movement is shorter than that of seeds.

From the above, it can be said that Japanese yam, Chinese yam, and bitter ginger combine the best aspects of asexual and sexual reproduction, thereby increasing their efficiency.

However, this still leaves a question: If that's the case, why doesn't *Dioscorea tokoro* reproduce asexually?

This has not yet been investigated. Dioscorea tokoro is a species that reproduces just as well as Dioscorea japonica, and it does not seem to suffer significant losses from losing the advantages mentioned above.

One possibility is that the African species D. sansibarensis has highly buoyant bulbils that spread by water currents, resulting in a wide distribution in valleys (Chen et al., 2022). Furthermore, D. alata is known to form bulbils when the soil becomes moist during the rainy season (Hamaoka et al., 2023).

Unlike seeds, bulbils are expected to be a more efficient way for plants to reproduce even in aquatic environments, and since *Dioscorea tokoro* is a species adapted to land, it may not need to produce bulbils.

In fact, the bitter oak, which is common in aquatic environments, does have bulbils. However, this is merely speculation.

How do they pollinate? The insects that visit them vary completely depending on the species!

All four species are dioecious, meaning they have separate plants that produce only male flowers and only female flowers. They all share six perianth segments, and male flowers have six stamens.

As mentioned above, it is an insect-pollinated flower, relying on insects for pollination. However, it gives the impression of being very inconspicuous compared to other insect-pollinated flowers. What kind of insects visit it?

It turns out that the flowers are actually visited by a special, very small insect that is perfectly sized for them.

In Japanese yam (Dioscorea japonica), the male inflorescences are erect from the leaf axils, while the female inflorescences droop, and the perianth segments are white and do not open very much (Hayashi et al., 2013). When 427 insects that visited these flowers were collected, 97% were found to be thrips, which are very small pollinating insects (Mizuki et al., 2005).

In Chinese yam (Dioscorea japonica), the male inflorescences are almost identical to those of Japanese yam (Dioscorea japonica), except for the drooping male inflorescences. A study conducted in China revealed that only one species of thrips, Ernothrips lobatus, visits the flowers (Li et al., 2014). This thrips also lays eggs and develops its larvae within the flowers, indicating a close relationship at the life cycle level. However, thrips can only move short distances, and pollination cannot occur unless males and females are in close proximity.

On the other hand, in Dioscorea tokoro, the male inflorescences are erect from the leaf axils, while the female inflorescences are drooping, and the perianth segments are pale green and spread flat (Kudo et al., 2021). When 389 insects that visited this flower were collected, 57% were gall midges and 11.6% were biting midges, but it was mostly biting midges that were actually carrying the pollen (Mochizuki et al., 2025).

Furthermore, despite the fact that both the male and female inflorescences of *Rhododendron parvifolium* droop and the perianth segments change from white to purple, a study in China found no records of insects visiting the flowers even once in two years, suggesting that it relies almost entirely on asexual reproduction via bulbils, with only a small portion being wind-pollinated (Li et al., 2014). It also rarely produces fruit in Japan (Kanagawa Prefecture Flora Survey Association, 2018).

Thus, we have obtained contrasting results: thrips visit Japanese yam and Chinese yam, small flies visit Japanese yam, and no insects visit bitter ginger. Although they are very similar in appearance, it can be said that their reproductive strategies are completely different.

What are the seed dispersal methods?

The fruits of all four species are capsules, possessing wings that make them more susceptible to wind, and the seeds also have wings (Kanagawa Prefecture Flora Survey Association, 2018; Chen et al., 2022).

As mentioned above, this is done to disperse seeds by wind, which has allowed the offspring to travel even greater distances than bulbils.

References

Chen, M., Sun, X., Xue, JY, Zhou, Y., & Hang, Y. (2022). Evolution of Reproductive Traits and Implications for Adaptation and Diversification in the Yam Genus Dioscorea L. Diversity, 14 (5), 349. https://doi.org/10.3390/d14050349

Hamaoka, N., Moriyama, T., Taniguchi, T., Suriyasak, C., & Ishibashi, Y. (2023). Bulbil formation on water yam (Dioscorea alata L.) is promoted by waterlogged soil. Agronomy, 13 (2), 484. https://doi.org/10.3390/agronomy13020484

Hayashi, Yasaka, Kadota, Yuichi, and Hirano, Takahisa. (2013). Yamakei Handy Illustrated Guide 1: Wildflowers (Revised and Expanded New Edition). Yama-kei Publishers. ISBN: 9784635070195

Inoue, Mizuki. (2007). Dispersion and spatial structure in dispersing clonal growth plants (bulbils, rhizomes, etc.)—comparison with non-dispersing clonal growth plants (rhizomes, stolons, projectiles). Journal of the Ecological Society of Japan, 57 (2), 238-244. https://doi.org/10.18960/seitai.57.2_238

Kanagawa Prefecture Flora Survey Association. (2018). Kanagawa Prefecture Flora 2018 Electronic Edition. Kanagawa Prefecture Flora Survey Association. ISBN: 9784991053726

Kudo, A., Sugihara, Y., Ota, A., & Terauchi, R. (2021). Upright males and drooping females—sexual differences in flower traits and visitor numbers in the dioecious plant Dioscorea tokoro. Abstracts of the Annual Meeting of the Ecological Society of Japan, 68, P1-061. https://esj.ne.jp/meeting/abst/68/P1-061.html

Mizuki, I., Ishida, K., Tani, N., & Tsumura, Y. (2010). Fine-scale spatial structure of genes and sexes in the dioecious plant Dioscorea japonica, which disperses by both bulbils and seeds. Evolutionary Ecology, 24 (6), 1399-1415. https://doi.org/10.1007/s10682-010-9396-z

Mizuki, I., Osawa, N., & Tsutsumi, T. (2005). Thrips (Thysanoptera: Thripidae) on the flowers of a dioecious plant, Dioscorea japonica (Dioscoreaceae). The Canadian Entomologist, 137 (6), 712-715. https://doi.org/10.4039/n05-003

Mizuki, I., & Takahashi, A. (2009). Secondary dispersal of Dioscorea japonica (Dioscoreaceae) bulbils by rodents. Journal of Forest Research, 14 (2), 95-100. https://doi.org/10.1007/s10310-008-0106-4

Mochizuki, K., Elsayed, AK, & Kawakita, A. (2025). Pollination by biting midges in Dioscorea tokoro and Vincetoxicum aristolochioides with a secondary contribution of gall midges: Pollination by biting midges in Dioscorea tokoro and Vincetoxicum aristolochioides with a secondary contribution of gall midges. Arthropod-Plant Interactions, 19 (3), 41. https://doi.org/10.1007/s11829-025-10142-4

Li, MM, Yan, QQ, Sun, XQ, Zhao, YM, Zhou, YF, & Hang, YY (2014). A preliminary study on pollination biology of three species in Dioscorea (Dioscoreaceae). Life Science Journal, 11 (2), 436-444. https://www.lifesciencesite.com/lsj/life1102/060_B00049life110214_436_444.pdf

Obidiegwu, JE, Lyons, JB, & Chilaka, CA (2020). The Dioscorea Genus (Yam): An appraisal of nutritional and therapeutic potentials. Foods, 9 (9), 1304. https://doi.org/10.3390/foods9091304

Takahashi, Akiko & Inoue, Mizuki. (2005). Comparison of dispersal distances of seeds and bulbils of *Dioscorea japonica*: Wind, gravity, and mice. Abstracts of the Annual Meeting of the Ecological Society of Japan, 52, 528. https://doi.org/10.14848/esj.ESJ52.0.528.0

Yoshida, M. (2019). Japanese people and sweet potatoes. Journal of Food and Nutrition Research, 39 (5), 235-248. ISSN: 0288-0806, https://ku-food-lab.com/wp/wp-content/uploads/2019/07/2774f33ed7e947fb03c1d40880e92a23.pdf

White magnolia, kobushi magnolia, star magnolia, and tamushiba all belong to the Magnolia genus of the Magnoliaceae family. As deciduous trees, they shed their leaves in winter, and a key characteristic is that around April, before the leaves appear like cherry blossoms, they produce large, white, polypetalous flowers, one per branch. These trees are common in cities and signal the arrival of spring, but they can be difficult to distinguish. Even in early spring when only the flowers are in bloom, they can be identified mainly by the number of petals, and later, the shape of the leaves also provides sufficient distinction. The flowers may appear primitive, but they actually possess various functions, such as protegry (female-first maturation), heat production, scent, and petal movement, which are specialized for attracting beetles. The fruit is oddly shaped and, when ripe, exposes red seeds that are dispersed by birds. This article will explain the white-flowered, deciduous Magnolia genus.

What are white magnolias, kobushi magnolias, star magnolias, and tamushiba magnolias?

White magnolia (Magnolia denudata) is a deciduous tree native to China that grows in forests and is widely planted in parks and gardens in Japan (Kanagawa Prefecture Flora Survey Association, 2018).

Magnolia kobus, also known as Kobushi, is a deciduous tree distributed in Hokkaido, Honshu, Shikoku, and Kyushu in Japan, as well as the Korean Peninsula. It is commonly found in deciduous forests and is widely planted in parks and gardens. There are two theories as to the origin of its name: one is that the shape of its buds or fruits resembles a "fist."

Magnolia stellata, also known as Shidekobushi or Himekobushi, is a deciduous shrub distributed in the central region of Honshu, Japan, and is often planted in parks and gardens. Its name comes from the fact that the shape of its petals resembles the "shide" (four-handed sticks) used in Shinto rituals.

Magnolia salicifolia, also known as Tamushiba (rice field insect leaf), is a deciduous tree distributed throughout Honshu, Shikoku, and Kyushu in Japan, and commonly found in mountainous areas along the Sea of Japan. There are two theories about the origin of its name: one is that it is named after the insect-like spots that appear on its leaves, and the other is that it was originally called "Kamushiba" (chewing bush) because the leaves have a unique sweet taste when chewed, which later evolved into "Tamushiba."

All of these species belong to the genus Magnolia in the family Magnoliaceae. As members of the Magnolia genus, they are characterized by elliptical to obovate leaves that are not shallowly lobed, and fruits that are aggregate fruits made up of follicles. In addition, these four species are deciduous trees, meaning they shed their leaves in winter and, around April, before the leaves emerge (unfold) like cherry blossoms, they produce large, white, polypetalous flowers, one per branch (terminally). The stamens and pistils inside are arranged spirally.

In Japan, they are often planted even in towns, and can be said to be a tree that, along with cherry blossoms, heralds the arrival of spring in the town.

However, since the flowers are the only visible feature of these four species during their peak season, it is often difficult to distinguish between them.

[Seed Plant Encyclopedia #028] What are the species of the Magnoliaceae family? Photo list

The Magnoliaceae family consists of evergreen or deciduous woody plants. The leaves are simple and alternate. The perianth segments are separate and whorled, exhibiting triperality. The stamens and pistils are numerous and arranged spirally. Approximately 300 species across two genera are known in the temperate and subtropical regions of Asia and America, with 7 species in one genus found in Japan...

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What are the differences between white magnolia, kobushi magnolia, star magnolia, and tamushiba magnolia?

First of all, as a premise, the white magnolia is an introduced species native to China, while the kobushi magnolia, shidekobushi magnolia, and tamushiba magnolia are native species, so you will not see white magnolias in the wild.

Furthermore, since Magnolia kobus is rarely planted as a park tree in Japan (Tamaki, 2020), the types you'll most likely see in town are Magnolia denudata, Magnolia kobus, or Magnolia stellata.

Next, we will consider the differences between the most commonly seen flowers (Kanagawa Prefecture Flora Survey Association, 2018).

In Magnolia stellata, the petal-like perianth segments are slender and there are more than 10 of them, whereas in Magnolia denudata, Magnolia kobus, and Magnolia salicifolia, there are 9 or fewer petal-like perianth segments.

The term "petal-like perianth segments" is just a technical term; you can think of them as simply the "petals" that we normally see.

Regarding the remaining three species, the difference lies in the fact that the white magnolia has nine broad petals, while the kobushi magnolia and tamushiba magnolia have six narrow petals.

The reason why the white magnolia appears to have nine "petals" is that three of its sepals (the parts that normally support the petals) have changed to resemble the color and shape of the actual petals. Magnolia kobus and Magnolia salicifolia have three small, normal green sepals. The term "petal-like perianth segments" used earlier is a roundabout expression because of this situation.

Because of these characteristics, the flowers of the white magnolia tightly enclose the inside without any gaps, whereas those of the kobushi magnolia and tamushiba magnolia appear sparse.

Regarding the remaining two species, the difference is that in Magnolia kobus, the tips of the perianth segments are blunt and there are small leaves just below the flower, while in Magnolia salicifolia, the tips of the perianth segments are somewhat acute and there are no small leaves just below the flower.

"Small leaves" refers to the new leaves that are just beginning to grow in preparation for the coming spring.

The leaves show even more distinct differences than the flowers (Hayashi, 2025).

While white magnolias, kobushi magnolias, and tamushiba magnolias have leaf tips that protrude, the star magnolia has leaf tips that are concave.

Regarding the remaining three species, the difference lies in the fact that while Magnolia kobus typically has long, slender leaves with sharply protruding, unequal-shaped tips, Magnolia denudata and Magnolia kobus have obovate leaves with rounded, bracket-shaped tips.

Regarding the remaining two species, the differences are that the white magnolia is large, has no wrinkles on the upper surface, the lateral veins on the lower surface are not prominent, and the leaf margin is flat without undulation, while the kobushi magnolia is small, has prominent wrinkles on the upper surface, prominent lateral veins on the lower surface, and the leaf margin is wavy and three-dimensional.

Are there any other similar types?

The genus Magnolia includes a great many species, such as purple magnolia, southern magnolia, and large-leaved magnolia, but only a very limited number are deciduous and produce white flowers.

Magnolia kobus f. pseudokobus is a species of kobushi-modoki (false kobushi magnolia) that has only been reported as a single individual in Tokushima Prefecture, Shikoku, where Magnolia kobus is not found. Furthermore, this wild individual is already extinct, and currently, clones propagated by cuttings are preserved outside of its natural habitat (Tamaki, 2021). Originally classified as Magnolia pseudokobus, recent research has revealed that it is a triploid, and it has now been reclassified as a cultivar.

Magnolia obovata is easily distinguishable from other trees because it flowers after its leaves have unfolded, its leaves are arranged almost in a whorl at the tips of its branches, and they are over 20 cm long.

Magnolia x soulangeana, also known as Sarasa Magnolia, Nishiki Magnolia, or Sotobeni Hakumokuren, is a hybrid of Magnolia denudata and Magnolia liliflora (a species with reddish-purple outer petals). Its petals are often pink to purple on the outside and white on the inside.

How is it pollinated? Is the claim that it's a "primitive flower" a lie?!

Magnoliaceae flowers are large and usually have numerous stamens and pistils arranged in a spiral. This characteristic is also found in Nymphaeaceae and Illiciaceae, and is often considered a primitive feature of Permian angiosperms (Higashi, 2004). In fact, recent molecular phylogenetic analyses have shown that magnoliids are a group that branched off quite early among angiosperms, and the existence of similar flower fossils seems to support this.

It is generally well known that large, simple white flowers like these are primarily pollinated by beetles (insects with hard wings, such as scarab beetles) (Higashi, 2004). Many species in the Magnoliaceae family also exhibit this characteristic, and it has been confirmed that beetles are indeed the primary visitors to their flowers.

For these reasons, the hypothesis that "the ancestors of angiosperms had flowers similar in shape to those of the Magnoliaceae family, and that primitive beetles visited and pollinated them in the very beginning, and that the flowers of the Magnoliaceae family are a remnant of that!" was strongly supported.

However, the prevailing view now is that these characteristics are derived traits from a botanical perspective, particularly within the Magnoliaceae family or parts of the Magnoliales order (Judd et al., 2008). In other words, the ancestors of angiosperms did not originally have such flower shapes; rather, these characteristics evolved independently of the Nymphaeaceae and Illiciaceae families.

Furthermore, from an entomological perspective, it has become clear that most existing groups of beetles originated during the Early Cretaceous period, when the Magnoliidae family arose (Hernandez-Vera et al., 2021).

For these reasons, it is believed that the flowers of the Magnoliaceae family evolved after a diverse range of beetles emerged. Beetles that parasitized gymnosperms gradually settled there, feeding, mating, and taking refuge within the flowers, which is thought to have promoted the diversification of Magnoliaceae flowers we see today.

In other words, the flowers of the Magnolia family are not remnants, but rather a new species that arose through parallel evolution.

Magnoliaceae flowers are known to exhibit protandry (female-first maturation), heat production, fragrance, and petal movement, and these features are thought to have evolved specifically for beetles.

Protigmatism is a phenomenon in which the sex of a flower changes over time, transitioning from a female phase to a male phase. While its effect on beetles is unknown, it is known that approximately 90% of protigmatism is pollinated by beetles, and it generally prevents self-pollination.

The flowers open during the female and male phases, and close during the period in between when pollen and nectar are produced, thereby controlling the entry and exit of beetles.

Thermogenesis in flower petals occurs in early spring when the petals reflect sunlight, warming the inside of the flower and providing warmth, which attracts beetles seeking thermal energy.

The four species of Magnolia mentioned above are no exception; it is believed that beetles play a central role in flower visitation, pollination, and fertilization.

There is still no specific research on white magnolias.

Magnolia kobus is known to be most effectively pollinated by several species of small beetles that forage for pollen (Ishida, 1996). Female flowers, which do not receive rewards, may be engaging in "hermaphroditism," mimicking male flowers, which do receive rewards.

It is known that Magnolia stellata is primarily pollinated by insects of the orders Coleoptera (Staphylinidae), Thysanoptera, and Diptera (Hirayama et al., 2005; Suzuki et al., 2009).

Magnolia salicifolia has been reported to be pollinated by various species including Hymenoptera (Bombus genus and bees), Coleoptera (Nitidulidae), and Diptera (Empididae and Syrphidae) (Yasukawa et al., 1992).

Despite these flowers being quite similar, the pollinating insects that visit them differ slightly. This may be related to subtle differences in the color and shape of the flowers, but as mentioned above, it has also been suggested that the scent of the flowers may play a role (Higashi, 2004).

It has been found that the white magnolia, which is native to China, strongly releases pentadecane, a type of hydrocarbon, as its main component (80-95%).

On the other hand, it has been found that the main components of Magnolia kobus, which is distributed mainly in Japan, are the terpenoid linalool (22%) and its oxides (66%), the main component of Magnolia hornbeam is methyl benzoate (100%), and the main components of Magnolia salicifolia are benzenoides such as 1,2-dimethoxybenzene (65%), benzyl alcohol (17%), and benzaldehyde (10%).

The relationship between these components and the insects they attract hasn't been specifically studied, but it may be an important factor.

What are the seed dispersal methods?

The fruit, common to the Magnolia genus, is an aggregate fruit composed of follicles. The aggregate fruit has an irregular shape, resembling an insect gall, and is a very unique shape not found in other plants.

The young aggregate fruit is an irregular green color, but as it ripens, it gradually turns red, and finally, each individual follicle of the brown aggregate fruit splits open, exposing bright red seeds. Some websites mistakenly refer to these red seeds as the "fruit," so please be aware of this error.

The reason for this misunderstanding is that these soft, red seeds can be split open, revealing hard, black, woody seeds underneath.

For a long time, there was a conflicting hypothesis as to whether this structure consists of a "red arilate" and a "black seed coat," or a "red fleshy seed coat (sarcotesta)" and a "black hard seed coat (sclerotesta)." It is now understood that the latter is true (Feng et al., 2024).

Magnolia seeds are dispersed by animal feeding. The red fleshy seed coat attracts animals, especially birds that can see red, while the black hard seed coat prevents the embryo from being digested after being eaten by birds. This allows the seeds to be dispersed over long distances, expanding their distribution and preventing competition with the parent tree.

The same is thought to be true for the four types mentioned above.

There is no data available on seed dispersal of white magnolia.

Magnolia kobus seeds are mainly dispersed by birds, although there have been reports of dispersal by martens (Tamaki, 2021).

The seeds of Magnolia stellata are dispersed by birds or gravity (Tamaki, 2016).

The seeds of Magnolia salicifolia are dispersed by birds and rodents (Tamaki, 2020).

References

Higashi, Koji. 2004. Scent and phylogenetic evolution of Magnoliaceae flowers. Classification 4(1): 49-61. https://doi.org/10.18942/bunrui.KJ00004649594

Feng, Q., Cai, M., Li, H., & Zhang, X. 2024. How seeds attract and protect: Seed coat development of magnolia. Plants 13(5): 688. https://doi.org/10.3390/plants13050688

Hayashi, Masayuki. 2025. Tree Leaves, 3rd Edition: Identifying 1390 Species Through Real-Life Scans. Yama-kei Publishers, Tokyo. 840pp. ISBN: 9784635070447

Hernandez-Vera, G., Navarrete-Heredia, JL, & Vazquez-Garcia, JA 2021. Beetles as floral visitors in the Magnoliaceae: an evolutionary perspective. Arthropod-Plant Interactions 15(3): 273-283. https://doi.org/10.1007/s11829-021-09819-3

Hirayama, K., Ishida, K., & Tomaru, N. 2005. Effects of pollen shortage and self-pollination on seed production of an endangered tree, Magnolia stellata. Annals of Botany 95(6): 1009-1015. https://doi.org/10.1093/aob/mci107

Ishida, K. 1996. Beetle pollination of Magnolia praecissima var. borealis. Plant Species Biology 11(2-3): 199-206. https://doi.org/10.1111/j.1442-1984.1996.tb00146.x

Judd, WS, Campbell, CS, Kellogg, EA, Stevens, PF, Donoghue, & MJ 2008. Plant Systematics: A Phylogenetic Approach (3rd ed.). Sinauer Associates Inc., Sunderland. 611pp. ISBN: 9780878934072

Kanagawa Prefecture Flora Survey Association. 2018. Kanagawa Prefecture Flora 2018 (Electronic Edition). Kanagawa Prefecture Flora Survey Association, Odawara. 1803pp. ISBN: 9784991053726

Suzuki, Setsuko; Ishida, Kiyoshi; and Tomaru, Nobuhiro. 2009. Relationship between successful female reproduction in Magnolia stellata and pollinating insects. Abstracts of the Annual Meeting of the Ecological Society of Japan 56: PB2-647. https://www.esj.ne.jp/meeting/abst/56/PB2-647.html

Tamaki, Ichiro. 2016. Geographical genetic structure of forest trees in Japan (12) Magnolia stellata (Magnolia genus, Magnoliaceae). Forest Genetics and Breeding 5(2): 83-87. https://doi.org/10.32135/fgtb.5.2_83

Tamaki, Ichiro. 2020. Geographical genetic structure of forest trees in Japan (28) Magnolia salicifolia (Magnolia genus, Magnoliaceae). Forest Genetics and Breeding 9(3): 105-109. https://doi.org/10.32135/fgtb.9.3_105

Tamaki, Ichiro. 2021. Geographical genetic structure of forest trees in Japan (32) Magnolia kobus (Magnolia genus, Magnoliaceae). Forest Genetics and Breeding 10(2): 116-119. https://doi.org/10.32135/fgtb.10.2_116

Yasukawa, S., Kato, H., Yamaoka, R., Tanaka, H., Arai, H., & Kawano, S. 1992. Reproductive and pollination biology of Magnolia and its allied genera (Magnoliaceae). I. Floral volatiles of several Magnolia and Michelia species and their roles in attracting insects. Plant Species Biology 7(2-3): 121-140. https://doi.org/10.1111/j.1442-1984.1992.tb00225.x

European pumpkins, Japanese pumpkins, and pepo pumpkins are all annual vining plants belonging to the Cucurbitaceae family, Cucurbita genus. Originally from the Americas, they are very popular in Japan, playing an important role in both everyday meals and Halloween celebrations. However, the three species are often confused, and no websites clearly explain their differences. They can be distinguished by their leaves, flowers, and fruit stalks. To briefly summarize the differences in use, focusing solely on Japan: European pumpkins are currently the most common, with sweet, sticky fruit used in stews and salads. Japanese pumpkins were the dominant variety before World War II, characterized by their mild flavor, and were used in stews, but were eventually replaced by European pumpkins. However, Japanese pumpkins are still used for sweets. Pepo pumpkins were very minor, although varieties like the Kinshiuri exist, but after the war, they became more common with zucchini and Connecticut field pumpkins used for Halloween jack-o'-lanterns. Pumpkins are not native to Japan or the West; they originated in the Americas. Surprisingly, the Japanese pumpkin is the most common in the West. It is believed that the fruit was originally eaten and the seeds dispersed by large mammals like the now-extinct mastodon. This article will explain the classification, morphology, history, and culture of the genus Cucurbita.

What are European pumpkins, Japanese pumpkins, and pepo pumpkins?

The European pumpkin (Cucurbita maxima), also known as the Japanese pumpkin, is a climbing annual plant native to South America (Argentina and Bolivia) and cultivated worldwide for its edible fruit (RBG Kew, 2026).

Japanese pumpkin (Cucurbita moschata), also known as Oriental pumpkin or Boubra, is a climbing annual plant native to Central America (Belize, Guatemala, and Mexico) and cultivated worldwide for its edible fruit. Among the vast number of varieties, some of the most representative Japanese varieties include the crane-necked pumpkin (Tsurukubi Kabocha) var. luffiformis, whose fruit is long and slender with a neck resembling a crane's neck; the chrysanthemum-seat pumpkin (Kikuza Kabocha) var. meloniformis, whose fruit has deep vertical grooves and whose cross-section resembles a chrysanthemum flower; and the gourd-shaped Saikyo pumpkin (Tounasu/Shishigatani Kabocha) var. meloniformis 'Toonas'.

Cucurbita pepo, also known as pepo pumpkin, is a climbing annual plant native to Central America (Mexico) and cultivated worldwide for its edible and ornamental fruits. It boasts a vast number of varieties, including the edible zucchini subsp. pepo 'Melopepo', the horticultural variety and subspecies of the Connecticut field pumpkin subsp. pepo 'Connecticut field', which has oblate-spherical fruits used in jack-o'-lanterns, and the ornamental pumpkin subsp. texana (var. ovifera is a synonym), which has oddly shaped fruits (Gong et al., 2012).

Both are annual vines belonging to the Cucurbitaceae family, genus Cucurbita. They are creeping plants, and their most distinctive feature is their large, fleshy fruit, as well as their yellow, bell-shaped corollas, which are important characteristics from a taxonomic standpoint.

However, the incorrect naming conventions of "Japanese pumpkin" and "Western pumpkin," which do not reflect their origins, have led to the misconception that Japanese pumpkins are a native species and Western pumpkins came from the West.

This is based on the historical circumstances of how both species were introduced to Japan, but in reality, as mentioned above, they are native to the Americas and are neither Japanese nor Western in any way.

Moreover, despite the fact that European pumpkins, Japanese pumpkins, and pepo pumpkins are completely different species, they are treated as if they were separate varieties, and few websites point out specific morphological differences, further exacerbating the misunderstanding.

The pepo pumpkin is relatively obscure and not well-known. However, edible zucchini is a cultivated variety of pepo pumpkin, and the Connecticut Field Pumpkin, a cultivated variety of pepo pumpkin, is used for Halloween jack-o'-lanterns.

Because there are many cultivated varieties of these three types of pumpkins, the names "○○ pumpkin" are often used without explanation, leading to confusion.

What are the differences between European pumpkins, Japanese pumpkins, and pepo pumpkins?

Let's start by clarifying the biological and morphological differences between the three main types. While there are many varieties, biologically speaking, the three most common types are sufficient, and understanding just these three is all you need.

As a fundamental point, as mentioned above, their natural distribution differs: the European pumpkin is native to South America (Argentina and Bolivia), the Japanese pumpkin is native to Central America (Belize, Guatemala, and Mexico), and the pepo pumpkin is native to Central America (Mexico).

While it's undeniable that the three species evolved from a common ancestor, the fact that the European pumpkin is distributed primarily in South America suggests that the three species have completely separated without interbreeding in the wild.

We will consider the specific differences in form (Wu et al., 2011).

In Japanese pumpkins, the flower sepals are linear with leaf-like tips, and the fruit stalk expands significantly at the tip. In contrast, in European pumpkins and pepo pumpkins, the flower sepals are linear to linear-lanceolate with slender tips, and the fruit stalk does not expand significantly at the tip.

The description "the flower's sepals are linear with leaf-like tips" is a little difficult to understand, but it means that the sepals at the back of the flower extend slightly to the sides, increasing their surface area and making them somewhat similar in shape to ordinary leaves. In pumpkins and pepo pumpkins, the sepals are simple and slender.

The phrase "the stalk expands significantly at the tip" is also difficult to understand, but essentially, Japanese pumpkins have a circular, whitish indentation at the tip of the stalk where the fruit's stem ends, while European pumpkins and pepo pumpkins lack this, resulting in a flat, simple appearance. This is one reason why Japanese pumpkins look "bumpy." However, some varieties, such as the vine-necked pumpkin, have evolved in a way that makes this characteristic less noticeable.

Regarding pumpkins (Pumpkin serrulata) and pepo pumpkins (Pumpkin pepo), the differences are that in pumpkins, the leaf blades are kidney-shaped to spherical with nearly entire margins, the sepals are lanceolate, and the fruit pedicels lack angular grooves and do not thicken at the tip, while in pepo pumpkins, the leaf blades are triangular to ovate-triangular with 5 to 7 irregular lobes, the sepals are linear-lanceolate, and the fruit pedicels have angular grooves and are slightly thickened at the tip.

For this, looking at the shape of the leaves should be sufficient. You can understand it as simply this: European pumpkins have leaves that don't separate, while pepo pumpkins have leaves that do.

The fruit morphology is so diverse that it's not a reliable indicator for distinguishing between the three varieties. However, you can differentiate them if you remember the shape of each variety, and nowadays, you can easily identify the variety name using Google Image Search.

Other pumpkin varieties cultivated in Japan include Cucurbita ficifolia and Cucurbita argyrosperma, but these are less common in Japan, so we will omit them.

What's the difference between pumpkin and squash?

In English, pumpkins are sometimes referred to as "pumkin" or "squash."

However, this does not distinguish the three species biologically; "pumpkin" is a general term for varieties of pumpkins in the Cucurbita genus that have orange rinds, while "squash" is a general term for varieties of pumpkins in the Cucurbita genus that have green rinds.

Therefore, the most common variety of pumpkin in Japan is called squash. It's all a bit confusing, isn't it?

What are the differences in history and uses between European pumpkins, Japanese pumpkins, and pepo pumpkins?

The uses of European pumpkins, Japanese pumpkins, and pepo pumpkins vary considerably from country to country. Therefore, it's difficult to summarize them in a single sentence.

To summarize briefly, focusing solely on Japan, the European pumpkin is currently the most common, with sweet and sticky fruit used in stews and sweets. The Japanese pumpkin was the most common before World War II, characterized by its mild flavor, and was used in stews, but it was replaced by the European pumpkin. The Pepo pumpkin was very minor, although there are varieties like the Golden Melon, but after the war, it became common with zucchini and the Connecticut Field Pumpkin, also known as Jack-o'-lantern.

In Japan, the most common type of pumpkin is the European pumpkin, while in Europe, the most common is the Japanese pumpkin.

Each of the three varieties has undergone significant changes in form due to micro-evolution and selective breeding brought about by Native Americans through domestication (Bisognin, 2002; Spengler, 2020). Just like corn and tomatoes, the efforts of Native Americans are what have enriched our current diets.

It is highly valued for its enormous seeds and fruits, which are edible, but they weren't always that large.

First, it is thought that selection for larger seeds led to the development of larger fruits. Generally, bitter fruits contained non-bitter seeds, so it is thought that the seeds were the first to be used as food. Subsequently, immature fruits were selected for their non-bitter flesh, and mature fruits were selected for their non-bitter, starchy flesh and non-woody peel.

What are the uses of European pumpkins?

As mentioned above, the European pumpkin originates from South America and for a long time was not used by any people other than Native Americans. It began to spread to North America and the rest of the world after the "Columbian Exchange" following the arrival of Columbus (1492-) (Nee, 1990). Records show that various varieties were used by Native Americans in the 16th century. In Japan, two to three varieties were introduced from the United States in 1863, and many more varieties were introduced by the Hokkaido Development Commission in the early Meiji period, becoming established in various regions (Fujita, 2010).

Therefore, although it is called "Western pumpkin," it has no connection to the West in terms of its place of origin. This is a name unique to Japan, as it was introduced from the United States.

Moreover, European pumpkins require very high temperatures to grow and are not well-established in Northern Europe , the British Isles, or regions with short or cool summers (Boswell, 1949). Therefore, as will be explained later, Japanese pumpkins are used in European pumpkin pies! This fact is the source of much confusion.

The primary use of the European pumpkin is for its edible fruit. Compared to the Japanese pumpkin, the European pumpkin is characterized by its sticky texture (Izumi, 2006).

It is eaten in tropical America, Japan, and parts of the United States (Boswell, 1949), as well as in Africa, India, Bangladesh, and Myanmar (Ferriol & Nuez, 2004). It is particularly popular in Japan, where it is used almost interchangeably with the Japanese pumpkin (Nihonkabocha), which will be discussed later. It is used in dishes such as simmered pumpkin, pumpkin soup, pumpkin tempura, and thinly sliced pumpkin in salads. Ironically, in the West, the Japanese pumpkin is preferred as food, as will be discussed later.

Rich in nutrients, regardless of variety, it is an excellent source of highly beneficial dietary fiber and minerals such as potassium, calcium, phosphorus, magnesium, sulfur, silicon, iron, and zinc to supplement your diet (Czech et al., 2018).

Furthermore, according to records for varieties within Japan, a comparison of β-carotene equivalents per 100 g of edible portion shows that while the pepo pumpkin (Kinshiuri) contains 49 μg and the Japanese pumpkin contains 730 μg, the Western pumpkin contains 4000 μg, which is approximately 5.6 times more (Fujita, 2010).

Furthermore, while the vitamin C content of pepo pumpkin (Kinshiuri) is 11 μg and that of Japanese pumpkin is 16 μg, that of European pumpkin is approximately three times higher at 43 μg, exceeding the vitamin C content of large tomatoes.

Pumpkin seeds are also used for food and, when roasted, are rich in protein, fat, and vitamin B1.

What are the uses of Japanese pumpkins?

Japanese pumpkins, being native to Central America, were long used by Native Americans and were an important food plant, ranking second only to corn and beans in many parts of the American economy before the colonial era (Boswell, 1949). The flowers, seeds, and flesh were all edible.

However, unlike the European pumpkin, it was cultivated and used early on in North America by Native Americans, along with the pepo pumpkin. On the other hand, it never reached South America.

It was after the arrival of Columbus (1492-) and the "Columbian Exchange" that it began to spread throughout the world via Europe.

Japanese pumpkins can withstand drought and frost during their flowering season, and although they are tropical plants, they are more cold-hardy than European pumpkins, making them the most popular pumpkin variety in Europe. European pumpkin pies use Japanese pumpkins. They are also consumed in many countries, including the United States, Mexico, India, China, and Brazil (Men et al., 2021).

Japanese pumpkins arrived in Japan before European pumpkins. It is believed that the introduction of Japanese pumpkins began in 1542 when a Portuguese ship drifted ashore in Bungo Province, and in 1549, they presented Japanese pumpkins to Otomo Sorin, who applied for permission to trade (Nishi, 1980; Fujita, 2010).

Otomo Sorin was a samurai and daimyo of Bungo Province (present-day Oita Prefecture) from the Sengoku period to the Azuchi-Momoyama period. He is known for actively adopting Christianity and Western culture by conducting trade with the Nanban (Southern Barbarians) from Kyushu, which he ruled as a Christian daimyo.

It is well known that the word "kabocha" (pumpkin) originates from "Cambodia," and it is said that the pumpkins introduced by Portuguese ships at that time were produced in the country of Cambodia (post-Angkor Cambodia) (Aoba, 2000).

It is believed that the pumpkin arrived in Nagasaki in 1573, and its cultivation began to spread widely among farmers, gradually spreading throughout Japan. Varieties such as the Tsurukubi pumpkin, Kikuza pumpkin, and Shishigatani pumpkin originated from this indigenous variety. Other varieties include the Kurokawa pumpkin (Hyuga pumpkin) and the Kogiku pumpkin.

It seems that the Japanese pumpkin (Nihonkabocha) was named as such because it was introduced to Japan before the European pumpkin (European pumpkin) and many indigenous varieties developed and diversified. However, considering that it did not originally exist in Japan and has become a minor vegetable in Japan today, it can be said that the name is misleading.

During and after World War II in the Pacific, Japanese pumpkins were an important food source. While today we imagine simmered pumpkin dishes made with sweet Western pumpkins, back then, they were made with Japanese pumpkins and had a much milder flavor.

Although the aforementioned varieties remain as traditional vegetables, they may seem quite minor in Japan. However, considering that Japanese pumpkins are used in pumpkin puree, even though many are imported from overseas, and that they are frequently used as an ingredient in commercially available pumpkin pie mixes and in sweets and desserts sold around Halloween, they continue to be a part of our diet in various forms.

The current primary use of Japanese pumpkins is for their fruit. Compared to Western pumpkins, Japanese pumpkins are characterized by their milder flavor. This may be related to the fact that the carbohydrate content in the flesh of Japanese pumpkins is high at 78.641 TP3T, significantly higher than that of Western pumpkins (69.511 TP3T) (Men et al., 2021).

In addition to carbohydrates, dietary fiber (such as pectin), vitamins A, C, and E, it is also rich in minerals (such as manganese, magnesium, and potassium).

In Japan, as mentioned above, pumpkins are considered to have less nutritional value than European pumpkins and are therefore poorly regarded (Fujita, 2010). However, overseas, their nutritional content has been studied in detail and they are attracting attention (Men et al., 2021). This may be due to differences between Japanese and European varieties.

What are the uses of pumpkins?

The pepo pumpkin, also native to Central America (Mexico), was used by Native Americans, with the oldest known records dating back 8,000 to 10,000 years ago in Oaxaca, southern Mexico, and approximately 7,000 years ago in Ocampo, Tamaulipas, Mexico (Nee, 1990). Along with the Japanese pumpkin, it held a position second only to corn and beans in many parts of the pre-colonial American economy (Boswell, 1949). The flowers, seeds, and flesh were all edible.

It was after the arrival of Columbus (1492-) and the "Columbian Exchange" that the pepo pumpkin began to spread throughout North America and the rest of the world. There is a record of a variety of pepo pumpkin being described in Germany in 1552.

A vast number of varieties have been developed for edible and ornamental purposes (Gong et al., 2012), and it has become particularly popular in Italy, where the zucchini variety was created in the late 19th century. Unlike other pumpkins, it is harvested in the summer, and in Europe and America, it is considered a type of summer squash. Because the unripe fruit and flowers of zucchini, which are high in water content, are eaten, few people may realize that it is a type of pumpkin. Ratatouille, a French dish, is a representative dish that uses zucchini.

Also, the Jack-o'-lanterns used for Halloween are not made from European pumpkins, but from a variety of pepo pumpkin called Connecticut Field Pumpkin. The ornamental pumpkin, a subspecies of pepo pumpkin, is purely for decoration and does not taste good.

Halloween originated from the Samhain harvest festival of the Celts, which later incorporated Christian elements. Jack-o'-lanterns were made to ward off evil spirits by acting as substitutes, but originally sugar beets or turnips were used. Pumpkins began to be used around the time Celtic immigrants moved to the United States. The story of Jack is a fictional tale.

Pepo pumpkins were first introduced to Japan after the First Sino-Japanese War (1894-1895), with varieties from North China being brought in, but they did not become very popular (Nishi, 1980). The Kinshiuri variety, whose flesh separates into thin, thread-like strands, is likely from this period.

Rather, zucchini and Connecticut field pumpkins arrived in Japan after World War II as part of Western culture, through a completely different route, and became established without being recognized as pepo pumpkins (Izumi, 2006). Zucchini was first imported from the United States around the late 1970s (early 1970s) when Italian cuisine became popular (Nogyo Sangyo Bunka Kyokai, 2004).

While the primary use is for the edible fruit, zucchini is unique in that its flowers are also eaten (known as "flower zucchini"), and some varieties, such as Connecticut Field Pumpkins and Ornamental Pumpkins, are purely ornamental and not tasty to eat.

How are pumpkin seeds dispersed? Were pumpkin fruits eaten by extinct animals?!

Pumpkin fruits are nutritious and a savior for humans, but there is one big question (Kistler et al., 2015).

In the natural world, what animals eat the fruit and then disperse the seeds through their feces?

At first glance, you might think that wild animals could eat pumpkins once they're ripe, but even when ripe, pumpkins are covered in a hard rind and are inedible to most animals.

Furthermore, it is known that the fruit pulp produces cucurbitacin, a triterpenoid compound that is cytotoxic and has a strong bitter taste, thus repelling small mammals.

Moreover, even if they are eaten, unless the animal swallows the seeds whole, they won't end up in its feces, preventing the species from expanding its habitat. The worst-case scenario is when animals, like rats, only eat the seeds.

In fact, recent research suggests that pumpkins are not the ancestors of currently existing animals, but rather were eaten and dispersed by large mammals (megafauna) that lived on the American continent before the Holocene epoch.

In fact, intact pumpkin seeds have been found in the dung deposits of mastodons (primitive elephant-like creatures). It certainly seems that mastodons could easily eat the fruit by stepping on it.

All of these large mammals were driven to extinction by Native Americans after the Holocene epoch, but now Native Americans are acting as seed dispersers by cultivating them (Spengler, 2020).

This phenomenon, where the current environment and adaptations are out of sync, is called "ecological anachronism," and it is believed that the same phenomenon occurs in avocados, cacao, American mulberry, American honey locust, and sachalinensis.

References

Aoba, Takashi. 2000. Selected Works of Takashi Aoba, Vol. 1: Japanese Vegetables. Yasaka Shobo, Tokyo. 311pp. ISBN: 9784896944563

Boswell, VR 1949. Our Vegetable Travelers. The National Geographic Magazine 96(2): 145-216. ISSN: 0027-9358, https://www.plantanswers.com/publications/vegetabletravelers/index.html

Bisognin, DA 2002. Origin and evolution of cultivated cucurbits. Ciência Rural 32: 715-723. https://doi.org/10.1590/S0103-84782002000400028

Czech, A., Stępniowska, A., Wiącek, D., Sujak, A., & Grela, ER 2018. The content of selected nutrients and minerals in some cultivars of Cucurbita maxima. British Food Journal 120(10): 2261-2269. https://doi.org/10.1108/BFJ-10-2017-0599

Ferriol, M., Picó, B., & Nuez, F. 2004. Morphological and molecular diversity of a collection of Cucurbita maxima landraces. Journal of the American Society for Horticultural Science 129(1): 60-69. https://doi.org/10.21273/JASHS.129.1.60

Fujita, Satoshi. 2010. Cultural History of Keisen Vegetables (7): Pumpkins—Carotene-Rich Healthy Vegetables. Horticultural Culture 7: 42-49. ISSN: 1882-5044, https://keisen.repo.nii.ac.jp/records/934

Gong, L., Paris, HS, Nee, MH, Stift, G., Pachner, M., Vollmann, J., & Lelley, T. 2012. Genetic relationships and evolution in Cucurbita pepo (pumpkin, squash, gourd) as revealed by simple sequence repeat polymorphisms. Theoretical and Applied Genetics 124(5): 875-891. https://doi.org/10.1007/s00122-011-1752-z

Izumi, Mikio. 2006. How vegetables are eaten around the world and in Japan—the same vegetables differ greatly. Journal of the Japanese Society for Food Preservation Science 32(6): 297-304. https://doi.org/10.5891/jafps.32.6_297

Kistler, L., Newsom, LA, Ryan, TM, Clarke, AC, Smith, BD, & Perry, GH 2015. Gourds and squashes (Cucurbita spp.) adapted to megafaunal extinction and ecological anachronism through domestication. Proceedings of the National Academy of Sciences 112(49): 15107-15112. https://doi.org/10.1073/pnas.1516109112

RBG Kew. 2026. The International Plant Names Index and World Checklist of Vascular Plants. Plants of the World Online. http://www.ipni.org and https://powo.science.kew.org/

Salehi, B., Sharifi-Rad, J., Capanoglu, E., Adrar, N., Catalkaya, G., Shaheen, S., … & Cho, WC 2019. Cucurbita plants: from farm to industry. Applied Sciences 9(16): 3387. https://doi.org/10.3390/app9163387

Spengler, RN 2020. Anthropogenic seed dispersal: rethinking the origins of plant domestication. Trends in Plant Science 25(4): 340-348. https://doi.org/10.1016/j.tplants.2020.01.005

Nee, M. 1990. The domestication of cucurbita (Cucurbitaceae). Economic Botany 44(Suppl 3): 56-68. https://doi.org/10.1007BF02860475

Rural Culture Association. 2004. Encyclopedia of Vegetable Gardening (2nd Edition, Vol. 20: 70 Specialty Vegetables). Rural Culture Association, Tokyo. 434pp. ISBN: 9784540041235

Men , X., Choi, SI, Han, https://doi.org/10.1007/s10068-020-00835-2

Nishi, Sadao. 1980. All About Vegetables (4). Cooking Science 13(4): 271-279. https://doi.org/10.11402/cookeryscience1968.13.4_271

Wu, ZY, Raven, PH, & Hong, DY (Eds.). 2011. Flora of China (Vol. 19 Cucurbitaceae through Valerianaceae, with Annonaceae and Berberidaceae). Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis. ISBN: 9781935641049

I originally have a science background, but I enjoy reading world history content.

I've heard something that caught my attention. It's the theory that spices (spices excluding the stems, leaves, and flowers) don't have much antibacterial property, and that "spices were used to mask the smell of rotten meat." I've always been skeptical about whether this is true.

Our investigation has concluded that this theory is highly unfounded. The reason is that spices are too expensive for ordinary people to use.

The medicinal properties of spices themselves are diverse, including antibacterial, antioxidant, appetite-stimulating, and anti-inflammatory effects. However, the reason why wealthy people in Europe and America sought out spices from abroad during the Age of Discovery was likely for their exotic flavors and because they stimulated the secretion of addictive neurotransmitters (brain hormones) in the brain.

Ultimately, this develops into conspicuous consumption among the wealthy in Europe and America (consumption to flaunt wealth).

However, it is becoming clear that some spices can actually be used to mask the characteristic fishy smell, so they are not spoiled, but it is true that some spices can be used to eliminate fishy odors.

Another theory suggests that the antibacterial and antioxidant properties of spices, which enhance their preservation, were important. This is an explanation that you sometimes see in high school world history classes.

While it is true that spices have antibacterial properties, it is unlikely that there was a demand for them in Europe and America during the Age of Discovery. On the other hand, antibacterial properties were likely important in their places of origin.

This article will explain why the idea that spices were used to mask the smell of rotten meat is false, and the real reason why European countries sought spices during the Age of Discovery.

What are the differences between Japanese pepper (Zanthoxylum piperitum), Chinese pepper (Zanthoxylum sibiricum), and Japanese pepper (Zanthoxylum ailanthoides)? We'll explain how to distinguish between similar species! What are their uses? What insects visit the flowers? Birds apparently love the seeds because they don't find them spicy!?

Japanese pepper (Zanthoxylum piperitum), Japanese sansho, and Japanese sansho are common species in Japan, and Japanese pepper in particular remains an essential ingredient in cooking today. All belong to the genus Zanthoxylum in the Rutaceae family, and are very similar in that they have many thorns all over the plant and odd-pinnately compound leaves consisting of an odd number of leaflets. Japanese pepper has a distinctive aroma...

ecological-information.com

What's the difference between dill (yin-dill) and fennel (foeniculum vulgare)? An explanation of how to distinguish between similar species.

Dill and fennel both belong to the Apiaceae family, share a strong aroma throughout the plant, and are used both as herbs (leaves) and spices (fruits). Their leaves, in particular, are known as "fish herbs" and pair exceptionally well with fish dishes. Furthermore, they are also similar in morphology...

ecological-information.com

Why can we say that the theory that spices were used to mask the smell of rotten meat during the Age of Discovery is false?

Why is the claim that "spices were used to mask the smell of rotten meat" considered to have little basis in fact?

The biggest problem is that spices from the Age of Discovery were too expensive (Murphy, 2024).

Europe already had an abundance of native herbs used in cooking, such as sage, rosemary, and thyme, as well as strongly flavored vegetables like leeks and onions. However, "spices" (such as pepper, nutmeg, and cloves) could only be imported through the spice trade from the Middle East and Asia.

Exotic spices, popularized by returning Crusaders and pilgrims, were already in vogue as highly prized luxuries among the upper classes in the Middle Ages, even before the Age of Discovery. However, their relative rarity, prestige, and the long distances it took to reach tables in France and England made them extremely expensive. They were simply unaffordable for ordinary households.

Furthermore, most households could quickly slaughter and eat animals by raising livestock or fish, hunting, or commissioning these activities. Examples of livestock included geese, ducks, chickens, pigs, and sheep.

In addition, if you have any leftovers, there are preservation methods such as salting, smoking, drying, and honey-preserving. Jerky and ham are examples of this.

From the above, it can be concluded that medieval Europeans did not deliberately eat rotten meat.

However, it has been confirmed that essential oils extracted from the fruit (fennel seeds) of fennel (a type of spice native to the Mediterranean coast) and the kernels of nutmeg seeds (native to Southeast Asia) can actually eliminate the odor of meat and fish (Takahashi et al., 2004).

Therefore, while it remains possible that native European plants like fennel were used to remove animal or fishy odors, it's unlikely to be the smell of rotting meat.

Why did the misinformation spread?

Why did this claim circulate? An influential book is involved (Myers, 2006).

In 1939, J.C. Drummond and Anne Wilbraham published "The Englishman's Food: Five Centuries of English Diet," in which they suggested that the wealthy in medieval Europe (and cunning bakers and grocery shop owners) desperately needed spices, primarily because meat was starting to spoil and the spices masked the smell and flavor of stale ingredients.

However, Drummond was a biochemist, not an expert in medieval food culture. Furthermore, he assumed from the outset that medieval preservation techniques were rudimentary and that "the main purpose of spices was to mask flavors." His work lacked documentary evidence and relied heavily on misinterpretations and speculation.

However, the readability of his writing, combined with the authority he gained from his social standing, gave his books weight and made them an ideal reference for anyone wanting to casually research the history of food.

This theory, like a rumor spreading, created a chain of mentions where inaccurate information was repeated as if it were the truth.

Worst of all, the speaker heard the same inaccurate information from multiple sources, but failed to realize that it all stemmed from a single source, creating the misconception that this theory was the dominant one.

What was the real reason Europe sought spices from abroad during the Age of Discovery?

So what was the reason for seeking spices during the Age of Discovery (mid-15th to mid-17th centuries)?

The primary reason is probably that it's a "delicacy" and has an exotic taste.

This might seem a bit simplistic, but the tendency for wealthy people to become gourmets in search of new flavors and seek out rare ingredients is still observed today.

If it were simply delicious, that would be the end of it, but for example, although it is native to Central and South America, the capsaicin contained in the fruit of the chili pepper is known to stimulate the secretion of beta-endorphins and dopamine, which are types of neurotransmitters (brain hormones) in the brain and are also called brain narcotics, due to its spiciness (pain) (Fattori et al., 2016).

This can have an effect that, while not pathological, could be described as addiction.

Other examples of spices affecting brain hormones, although primarily based on animal studies, include the following:

These effects likely contributed to a stronger craving for spices (Le Couteur & Burreson, 2003=2011).

As trade further developed and spices became even more expensive, the use of spices evolved into a way for the wealthy in Europe and America to flaunt their wealth and demonstrate that they could afford to use expensive spices on a daily basis (Freedman, 2005).

This corresponds to what is called "constancy consumption" in economics. This is not merely "showing off," but has been theorized in evolutionary biology as "handicap theory," and is known as an important motivation for consumption in humans (Miller, 2009=2017).

As described above, the reasons for seeking spices during the Age of Discovery likely evolved from the pursuit of delicacies to addiction and then to conspicuous consumption.

The reason Europe went to the trouble of obtaining spices by sea was that in the 15th century, the Ottoman Empire destroyed the Byzantine Empire and expanded into the Eastern Mediterranean, imposing extremely high tariffs. As a result, the supply of spices that had originally come in through the Eastern trade (Levant trade) between Islamic Qalimi merchants and Italian merchants in Venice was cut off.

As a result, the Portuguese and Spanish efforts to find spices unaffected by the Islamic world spread to the imperialist powers of the Netherlands, Britain, France, Germany, America, Italy, and Belgium, leading to colonial rule by Western powers around the world.

Is the antibacterial properties of spices related to the demand for spices?

However, and this is a bit complicated, while the reasons why Europeans and Americans sought spices during the Age of Discovery can be attributed to the pursuit of delicacies, their addictive nature, and their conspicuous consumption, the reasons why the indigenous people of those colonies used spices are likely different.

For the local people, unlike Westerners, spices grew naturally, were inexpensive, and were deeply integrated into their customs and food culture.

While taste and addictive properties are certainly contributing factors, the reasons for its long-term integration into the culture likely include its lipid-derived antioxidant, antibacterial, insecticidal, and animal-repellent properties, as well as its appetite-stimulating, anti-inflammatory, and odor-masking effects (Gottardi et al., 2016). Furthermore, although scientific proof is still lacking, it was also expected to play a role as a herbal medicine for specific organs.

In particular, antioxidant and antibacterial properties are thought to have been important for improving the preservation of food and for embalming corpses. Antibacterial properties have been proven in 99 major spices, including pepper, chili peppers, cloves, nutmeg, and sansho pepper.

Such antibacterial effects may not have been particularly valued in the European and American countries during the Age of Discovery.

However, as Dutch-Asian trade progressed from the 17th to the 18th centuries, and as a result of the expansion of trade and competition among merchants and companies, the prices of many commodities began to converge between regions. Colonial goods such as spices, tea, and sugar also spread to the general households in Europe and America (De Zwart, 2016), and became commonly consumed by ordinary households.

In Japan, after the Meiji Restoration (1853), spices originating from South America, such as chili peppers, were added to the existing Asian spices.

At this stage, some people may have started to become aware of its antibacterial properties and health benefits.

Since then, scientific research has advanced, proving that it actually has functions such as antibacterial properties and health benefits, and it has once again attracted attention.

Thus, the role of spices has changed in complex ways depending on the region and era. While the theory that spices were consumed for their odor-masking or antibacterial properties during the "Age of Discovery" is rather weak, it's important to note that spices themselves do have those effects.

References

Chauhan, S., Tiwari, A., Verma, A., Padhan, PK, Verma, S., & Gupta, PC 2024. Exploring the potential of saffron as a therapeutic agent in depression treatment: a comparative review. The Yale Journal of Biology and Medicine 97(3): 365-381. https://doi.org/10.59249/XURF4540

De Zwart, P. 2016. Globalization in the early modern era: new evidence from the Dutch-Asiatic trade, c. 1600–1800. The Journal of Economic History 76(2): 520-558. https://doi.org/10.1017/S0022050716000553

Fattori, V., Hohmann, MS, Rossaneis, AC, Pinho-Ribeiro, FA, & Verri Jr, WA 2016. Capsaicin: current understanding of its mechanisms and therapy of pain and other pre-clinical and clinical uses. Molecules 21(7): 844. https://doi.org/10.3390/molecules21070844

Freedman, P. 2005. Spices and late-medieval European ideas of scarcity and value. Speculum 80(4): 1209-1227. https://doi.org/10.1017/S0038713400001391, https://gebeasley.org/famished/wp-content/uploads/2015/10/document-2-1.pdf

Garabadu, D., Shah, A., Ahmad, A., Joshi, VB, Saxena, B., Palit, G., & Krishnamurthy, S. 2011. Eugenol as an anti-stress agent: modulation of hypothalamic-pituitary-adrenal axis and brain monoaminergic systems in a rat model of stress. Stress 14(2): 145-155. https://doi.org/10.3109/10253890.2010.521602

Gottardi, D., Bukvicki, D., Prasad, S., & Tyagi, AK 2016. Beneficial effects of spices in food preservation and safety. Frontiers in Microbiology 7: 186557. https://doi.org/10.3389/fmicb.2016.01394

Hidayat, R., Wulandari, P., & Reagan, M. 2022. The potential of cinnamon extract (Cinnamomum burmanii) as anti-insomnia medication through hypothalamus pituitary adrenal axis improvement in rats. Acta Medica Academica 51(2): 79-84. https://doi.org/10.5644/ama2006-124.375

Kim, CY, Seo, Y., Lee, C., Park, GH, & Jang, JH 2018. Neuroprotective effect and molecular mechanism of [6]-Gingerol against scopolamine-induced amnesia in C57BL/6 mice. Evidence-Based Complementary and Alternative Medicine 2018(1): 8941564. https://doi.org/10.1155/2018/8941564

Kulkarni, SK, & Dhir, A. 2010. An overview of curcumin in neurological disorders. Indian Journal of Pharmaceutical Sciences 72(2): 149-154. https://doi.org/10.4103/0250-474X.65012

Le Couteur, PC, & Burreson, J. 2003. Napoleon's buttons: How 17 molecules changed history. Tarcher, 384pp. ISBN: 9781585422203 [=2011. Spices, explosives, pharmaceuticals—17 chemical substances that changed world history. Chuokoron-Shinsha, Tokyo. 368pp. ISBN: 9784120043079]

Li, S., Wang, C., Li, W., Koike, K., Nikaido, T., & Wang, MW 2007. Antidepressant-like effects of piperine and its derivative, antiepilepsirine. Journal of Asian Natural Products Research 9(5): 421-430. https://doi.org/10.1080/10286020500384302

Miller, G. 2009. Spent: Sex, Evolution, and Consumer Behavior. Viking Adult, 384pp. ISBN: 9780670020621 [=2017. Consumer Capitalism! The Evolutionary Psychology of Show-offs. Keisou Shobo, 480pp. ISBN: 9784326299256]

Murphy, D. 2024, October 29. Did Medieval Kings Need Spice to Cover Up Rotten Food?. Youth in Food Systems. https://seeds.ca/schoolfoodgardens/13837-2/

Myers, D. 2006. Drummond's Rotten Meat: When Good Sources Go Bad. Medieval Cookery. https://www.medievalcookery.com/notes/drummond.pdf

Seneme, EF, Dos Santos, DC, Silva, EMR, Franco, YEM, & Longato, GB 2021. Pharmacological and therapeutic potential of myristicin: A literature review. Molecules 26(19): 5914. https://doi.org/10.3390/molecules26195914

Takahashi, YK, Nagayama, S., & Mori, K. 2004. Detection and masking of spoiled food smells by odor maps in the olfactory bulb. Journal of Neuroscience 24(40): 8690-8694. https://doi.org/10.1523/JNEUROSCI.2510-04.2004

Xu, J., Xu, H., Liu, Y., He, H., & Li, G. 2015. Vanillin-induced amelioration of depression-like behaviors in rats by modulating monoamine neurotransmitters in the brain. Psychiatry Research 225(3): 509-514. https://doi.org/10.1016/j.psychres.2014.11.056

Both Japanese broom (Cytisus scoparius) and dwarf broom (Cytisus erythrosora) belong to the legume family and are classified under the genus Cytisus in Japan. They are characterized by their small, trifoliate compound leaves and yellow, butterfly-shaped flowers that bloom in spring. In horticulture, they are cultivated for ornamental purposes, but dwarf broom is increasingly being sold under the name "Japanese broom," leading to more confusion. However, there is a crucial difference in the leaves, and checking this will prevent any mistakes. Japanese broom flowers are known to "burst" to release pollen onto bees. This article will explain the classification, morphology, and ecology of the genus Cytisus.

What are Broom and Cryptomeria japonica?

Cytisus scoparius, also known as broom or scoparius, is a deciduous shrub native to Europe that is cultivated worldwide for ornamental purposes and sometimes escapes cultivation. In Japan, it is commonly cultivated in gardens as an ornamental plant and sometimes escapes cultivation and becomes naturalized (Hayashi, 2019).

Genista x spachiana, also known as dwarf broom (Genista canariesis), is an evergreen shrub that is a horticultural hybrid of Genista canariesis and Genista stenopetala, native to the Canary Islands (off the northwest coast of Africa, a Spanish territory) (Sheppard et al., 2006). While the Ylist uses the scientific name Cytisus x spachianus, it is generally classified under the genus Genista. It is grown in warmer climates as a potted plant or garden tree.

Both belong to the legume family and are classified under the genus *Cytisus* in Japanese classification. They are characterized by having small, trifoliate compound leaves and producing yellow, butterfly-shaped flowers in the spring.

The Japanese name, originally genst or ginst in Dutch (derived from the Latin genista), was introduced to Japan during the Kyoho era of the Edo period. In Dutch studies books, it began to be written as enista, which later became enisuda with a voiced consonant, and the form genisuda appeared later, but ultimately it became enishida (Maeda, 2005).

Both are cultivated as ornamental plants in gardens, but many people may not be able to distinguish between the two species. The dwarf broom (Cytisus scoparius) is increasingly being sold under the name "Broom," leading to more confusion. They originate from different regions and are completely different species, so we want to reduce such misunderstandings.

What is the difference between Broom (Cytisus scoparius) and Dwarf Broom (Cytisus scoparius)?

The main difference between broom (Cytisus scoparius) and dwarf broom (Cytisus scoparius) lies primarily in their leaves (Hayashi, 2019).

Specifically, in broom (Cytisus scoparius), many leaves lack petioles, and there is a mixture of trifoliate and undivided leaves. The leaf tips are pointed, there are few hairs, and the leaves are dark green. In contrast, dwarf broom (Cytisus scoparius) has distinct petioles, only trifoliate leaves, the leaf tips are rounded, there are many hairs, and the leaves are light green.

Overall, broom (Cytisus scoparius) has a stiff appearance, and its leaves often grow straight upwards at an angle, but dwarf broom (Cytisus scoparius) has a softer appearance, and its leaves tend to droop.

Among the broom species, there is also the red-cheeked broom, Cytisus scoparius 'Andreanus', which has red keel petals on its flowers.

Currently, perhaps because of the abundance of flowers, the number of dwarf broom plants has increased considerably.

The "Ginette" in Plantagenet's name refers to the broom plant!?

Broom (Cytisus scoparius) has strong ties to European culture, and its yellow flowers are known as "golden flowers," highly valued for their beauty and hardiness.

The Plantagenet dynasty, which ruled England from 1154 to 1399, began when Henry II, Count of Anjou, of France, ascended to the English throne. The name Plantagenet comes from the French word "plante genêt," meaning "broom plant," and the word "genêt" comes from the Latin word "genista," meaning "broom."

As mentioned above, the Japanese word "enishida" can also be traced back to "genista," so they actually share the same etymology.

There are several theories as to why the name of the royal family was used for the broom plant. The most famous is that it was the nickname of Geoffrey V, Count of Anjou, the father of Henry II, Count of Anjou, and that he wore a broom plant in his hat.

While it is confirmed that it was a nickname for Geoffrey V, Count of Anjou, the story of him "wearing a broom in his hat" only became popular in the 16th and 17th centuries, and its etymological basis is weak. It has been suggested that it may have spread as a symbolic interpretation in later times (Plant, 2007).

One paper that points this out argues that while the possibility of using broom as a stab cannot be ruled out, it may have been used as a symbol of strong vitality, growth, and reproductive power, given its hairy buds and sturdy branches.

How is it pollinated? Do broom flowers "burst"?!

The pollination method of broom is typical of legumes, with butterfly-shaped flowers, and it is an insect-pollinated flower like other legumes (Tanaka and Hirano, 2000; Tanaka, 2001).

However, the pollination method is slightly different.

Butterfly-shaped flowers are divided into the standard petal (upper petal) and the wing petals (outer petals) and keel petals (inner petals) of the lower petals, and it is known that the wing petals reflect ultraviolet light.

In other words, while it appears as a uniformly yellow flower to humans, insects see the underside of the flower as having color.

Bees such as bumblebees, honeybees, and long-horned bees recognize these as nectar guides and are attracted to them, attempting to drink the nectar. However, broom flowers actually do not contain nectar.

The bee uses its middle and hind legs to brace itself on the keel petal of the broom flower, and this stimulation causes the keel petal to suddenly burst open, slamming the stamens and pistil that were contained within in a spring-like structure.

In this way, the broom plant successfully pollinates bees by sprinkling pollen from the tips of its stamens onto them, and by allowing pollen from other bees on their backs to adhere to the brooms.

It might seem that the lack of nectar is a disadvantage for the bees, but pollen is an important source of protein, so it's likely that the bees come specifically for this purpose.

References

Hayashi, Masayuki. (2019). Tree Leaves: Expanded and Revised Edition - Identifying 1300 Species Through Real-Life Scans. Yama-kei Publishers. ISBN: 9784635070447

Maeda, Tomoki. 2005. The Complete Dictionary of Japanese Etymology. Shogakukan. ISBN: 9784095011813

Plant, JS (2007). The tardy adoption of the Plantagenet surname. Nomina, 30, 57-84. ISSN: 0141-6340, https://www.snsbi.org.uk/Nomina_articles/Nomina_30_Plant.pdf

Sheppard, A., Haines, M., & Thomann, T. (2006). Native-range research assists risk analysis for non-targets in weed biological control: the cautionary tale of the broom seed beetle. Australian Journal of Entomology, 45 (4), 292-297. https://doi.org/10.1111/j.1440-6055.2006.00553.x

Tanaka, Hajime. (2001). Flowers and Insects: A Collection of Discoveries of Mysterious Deception. Kodansha. ISBN: 9784062691437

Tanaka, Hajime & Hirano, Takahisa. (2000). The Face of Flowers: Wisdom for Bearing Fruit. Yama-kei Publishers. ISBN: 9784635063043

Black nightshade, large black nightshade, American black nightshade, and glossy black nightshade all belong to the Solanaceae family and Solanum genus. They are very common in urban areas and can even be found in green spaces in large cities. They are characterized by their round, black ripening fruits, but the four species are very similar and sometimes difficult to distinguish. Various identification methods have been proposed, but I think focusing on the characteristics of the flowers and fruits is the simplest. Sometimes, you may just have to accept that there are individuals that are indistinguishable. This article will explain the classification and morphology of the Solanum genus, which produces round, black fruits.

What are black nightshade, large black nightshade, American black nightshade, and glossy black nightshade?

Solanum nigrum, also known as black nightshade or dog nightshade, is an annual plant widely distributed in Hokkaido, Honshu, Shikoku, Kyushu, and the Ryukyu Islands in Japan; Eurasia; and naturalized in the Americas (Kanagawa Prefecture Flora Survey Association, 2018; RBG Kew, 2025). In Japan, it grows along roadsides, cultivated fields, wastelands, and riverbanks.

Solanum nigrescens, also known as large black nightshade, is an annual or perennial plant native to the southern United States, Central America, and northern South America, and has naturalized throughout the world. In Japan, it grows not only in urban areas south of Honshu, but also in riverbeds, cultivated fields, and forest edges in areas slightly closer to mountains.

American nightshade (Solanum emulans) is an annual plant native to Canada and the eastern United States, and has naturalized in Europe and Japan. It grows in harbors and fields throughout Japan. Older literature, such as the "Flora of Kanagawa Prefecture 2018," identifies it as Solanum ptychanthum, but this is now considered a synonym (old scientific name) (Knapp et al., 2019).

Solanum americanum, also known as glossy-fruited black nightshade, is an annual or perennial plant native to Canada and South America that has naturalized worldwide. In Japan, it grows around farmland, riverbanks, coastlines, and forest edges at the foot of mountains.

All of these plants belong to the Solanum genus of the nightshade family, and they are very common in urban areas, and can even be found in green spaces in large cities.

It possesses the characteristic "porous anthers" of the Solanum genus, with large, conspicuous yellow anthers that taper towards the tip and have small holes.

In addition, these four species are characterized by polymorphic leaves, small flowers, and nearly spherical fruits that ripen to purple to black.

The four species mentioned above are very similar and difficult to distinguish. It would be almost impossible to identify them at a glance while walking in the wild.

Furthermore, the existence of various intermediate forms makes accurate identification difficult.

What are the differences between *Solanum nigrum*, *Solanum sibiricum*, *Solanum nigrum*, and *Solanum nigrum*?

Various methods for identifying these four species have been suggested in numerous field guides and websites.

However, the sheer number of points of focus can actually make identification more difficult.

Therefore, I will focus on explaining only the truly important points here (Kanagawa Prefecture Flora Survey Association, 2018).

First, there is a difference in that the corolla of the black nightshade (Solanum nigrum) is shallowly incised, while that of the large black nightshade (Solanum nigrum), American black nightshade (Solanum sempervirens), and glossy black nightshade (Solanum nigrum var. sempervirens), the corolla is deeply incised, extending almost to the base.

Regarding the remaining three species, the fruits of *Solanum nigrum* and *Solanum americanum* are 7-10 mm in diameter, black with a somewhat dull sheen, and the flesh remains green until fully ripe. In contrast, *Solanum sempervirens* has fruits that are 4-7 mm in diameter, ripen to a dark purple color with a strong sheen, and the flesh turns purple earlier.

Regarding the remaining two species, there is a difference in that *Solanum nigrum* has 5 to 8 flowers per inflorescence and the corolla is large, with a diameter of 8 to 12 mm, while *Solanum americanum* has 1 to 4 flowers per inflorescence and the corolla is 4 to 6 mm in diameter.

I think the basic approach is to simply observe the above points. While field guides often mention examining the number of spherical granules and seeds within the fruit, this is not practical for the average person to observe in the field, so I will omit it here. For more detailed information, please refer to the Kanagawa Prefectural Flora Survey Association (2018) or Knapp et al. (2019).

However, there are intermediate individuals, and it can be difficult to distinguish between *Solanum nigrum* and *Solanum americanum* in particular. The notches in the corolla that identify *Solanum nigrum* can also be difficult to discern from certain angles, as the corolla is small and requires careful examination of multiple specimens.

Flower color and the curvature of the corolla lobes are individual variations and should not be used as a reference.

Are there any other similar species?

The Solanum genus includes several species with "black nightshade" in their name, such as Solanum sarrachoides, Solanum physalifolium var. nitidibaccatum, Solanum villosum subsp. villosum, and Solanum villosum subsp. miniatum.

However, in *Solanum nigrum* and *Solanum humile*, the calyx enlarges after flowering, covering half or more of the fruit, so their appearance is quite different.

The fruits of both the velvet nightshade and the red nightshade are elongated ellipsoids and ripen to yellow to red, so there's no chance of confusion.

Other species in the Solanum genus are larger, have different fruit shapes, or are thorny, so they are unlikely to be confused. Please see the separate article for more details. In the case of the Chinese lantern plant, the fruit is enclosed by a persistent calyx.

What are the differences between ground cherries, edible ground cherries (strawberry tomatoes), and tomatoes? We'll explain how to distinguish between similar varieties! Are three types of "edible ground cherries" being confused?

Ground cherries, edible ground cherries (strawberry tomatoes), and tomatoes all belong to the nightshade family and are characterized by producing red fruits. Edible ground cherries are sold under names such as "edible ground cherry" and "strawberry tomato," and there is some confusion about their relationship to ground cherries and tomatoes...

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What are the differences between eggplant and nightshade? What is the origin and evolution of eggplant? Why is nightshade disliked? Does its flower pollinate by vibration? Why are nightshade fruits poisonous?

Both eggplant (Nasu) and nightshade (Nightshade japonica) share the name "eggplant" and have similar flower shapes, so those unfamiliar with them might confuse them. However, eggplant and nightshade are completely different species. Eggplant is a cultivated plant that does not grow wild and has no thorns, while nightshade is a wild plant...

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What are the differences between Solanum lyratum, Solanum sarmentosum, Solanum sarmentosum, and Solanum jasminoides? We'll explain how to distinguish between similar species! What are the structures of their flowers and fruits?

Solanum lyratum, Solanum sarmentosum, Solanum japonica, and Solanum jasminoides all belong to the Solanaceae family and are four species that share the characteristic of being "climbing plants." Their basic flower and fruit structures are the same, which is why they are often confused. However, these four species have clear differences...

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What are the differences between *Tama coral* (winter coral) and *Himeta coral*? An explanation of how to distinguish between similar species.

Both Solanum sieboldii (winter coral) and Solanum nigrum belong to the Solanaceae family and are cultivated extensively for ornamental purposes because they produce attractive, round, red, ripe fruits (berries) in winter. However, in Japan, it is not always possible to properly distinguish between the two varieties, Solanum sieboldii and Solanum nigrum...

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References

Kanagawa Prefecture Flora Survey Association. 2018. Kanagawa Prefecture Flora 2018 (Electronic Edition). Kanagawa Prefecture Flora Survey Association, Odawara. 1803pp. ISBN: 9784991053726

Knapp, S., Barboza, GE, Bohs, L., & Särkinen, T. 2019. A revision of the Morelloid clade of Solanum L. (Solanaceae) in North and Central America and the Caribbean. PhytoKeys 123: 1-144. https://doi.org/10.3897/phytokeys.123.31738

RBG Kew. 2025. The International Plant Names Index and World Checklist of Vascular Plants. Plants of the World Online. http://www.ipni.org and https://powo.science.kew.org/