Styrax japonica, Pink Chime, and Styrax obassia all belong to the Styrax genus of the Styracaceae family and are familiar plants often found in gardens. Morphologically, a characteristic feature is that the flower stalks grow downwards towards the ground, and the flowers bloom facing downwards. However, some people may not know how to distinguish between them. Pink Chime is a horticultural variety of Styrax japonica, and the only difference is that the flowers are pink. Styrax japonica and Styrax obassia are completely different species and can be distinguished by the shape of their leaves and how their flowers are arranged. In addition, plants such as Chishanoki, Deutzia, Symplocos chinensis, and Stewartia pseudocamellia are often searched along with Styrax japonica, but Chishanoki is simply a name confusion, and Deutzia, Symplocos chinensis, and Stewartia pseudocamellia only have slightly similar flower colors and are not easily mistaken for each other if you look closely. This article will explain the classification of the Styrax genus.

What are Styrax japonica, Pink Chime, and Styrax obassia?

Styrax japonicus, also known as the Japanese snowbell tree (Egonoki or wild jasmine), is also called Rokurogi, Chishanoki, or Yamachis. It is a deciduous small tree distributed in Hokkaido (eastern), Honshu, Shikoku, Kyushu, the Ryukyu Islands, Korea, and China, growing in mixed forests at the foot of mountains, in mountain valleys, and along streams (Kanagawa Prefecture Flora Survey Association, 2018). Although its scientific name is written as Styrax japonica in various media such as the Japanese Wikipedia, according to Ylist, this is an old scientific name (synonym). Styrax japonicus is used worldwide (RBG Kew, 2023).

Styrax japonicus 'Pink Chimes', also known as Pink Chimes, Red-flowered Styrax, or Beni-ego, is a cultivated variety of Styrax japonicus grown in Japan and does not grow wild.

Styrax obassia, also known as white cloud tree, is also called large-leaved lettuce. It is distributed in Hokkaido, Honshu, Shikoku, Kyushu, Korea, and China, and is a deciduous small tree or tree that grows in hills and mountainous areas.

All of these plants belong to the genus Styrax in the family Styracaceae, and are familiar plants that are often cultivated in gardens and other horticultural purposes.

Morphologically, the main common features are that the flower stalks extend downwards towards the ground, the white flowers usually bloom facing downwards, and the corolla lobes are arranged in a tile-like pattern. Another common feature is the presence of stellate hairs on the underside of the leaves.

However, some people may not know how to distinguish between them.

What are the differences between Styrax japonica, Pink Chime, and Styrax obassia?

First and foremost, Pink Chime is simply a cultivated variety of Styrax japonica, so there are no fundamental structural differences between Styrax japonica and Pink Chime. However, it is significantly different from another species, Styrax obassia.

Specifically, the differences are that in Styrax japonica and Pink Chime, the leaves are somewhat rhombic-ovate (rarely lanceolate) and small, and the flowers are only 1 to 4 at the end of long pedicels, while in Styrax obassia, the leaves are round and large, often with fangs at the tip, and the flowers are numerous with short pedicels forming a raceme.

A peduncle (or stem) is the thin part that connects the flower to the plant body.

Another difference between wild Styrax japonica and Styrax obassia is that Styrax japonica grows from lowlands to mountainous areas, while Styrax obassia usually grows in mountainous areas.

The difference between Styrax japonica and Pink Chime is slight: Styrax japonica has white flowers, while Pink Chime has pink flowers. Pink Chime does not grow wild.

In addition, there is another species called Styrax shiraiana, which is distributed in the Kanto region (including Tochigi Prefecture), Shikoku, and Kyushu, and is very similar to Styrax obassia. However, its leaves are smaller, around 7 cm in diameter compared to Styrax obassia's 15 cm, and usually have large serrations, so they are not perfectly round (Hayashi, 2019). Furthermore, it has fewer stellate hairs on the underside of the leaves, the inflorescence is shorter, the flowers are smaller, and the tree height is somewhat lower, around 3 to 7 m.

There is also a variety of Styrax japonicus f. pendulus, which has drooping branches and leaves. It is sometimes used in bonsai.

The variety Styrax japonicus var. kotoensis, also known as red-headed styrax, is distributed in Kyushu (south of the Tokara Islands) to Okinawa in Japan, as well as in Taiwan and the Philippines. It was previously thought to be distinguishable from Styrax japonica by its slightly larger flowers and fruits, less prominent leaf serrations, and much earlier flowering period (autumn to spring). However, recent research has concluded that it is indistinguishable from Styrax japonica and treats them as the same species (Ohashi et al., 2017).

What is the difference between Styrax japonica and Styrax japonica?

The difference between Styrax japonica and Lettuce (Styrax japonica) is also a frequently searched topic.

The name "Chishanoki" (meaning "lettuce tree") has two confusing meanings.

First, let's look at another name for the Styrax japonica tree. In this case, we can say that "Styrax japonica = Chishanoki." In the Kabuki play "Kyara Sendai Hagi," a plant called Chishanoki appears, and this plant is actually Styrax japonica.

However, secondly, from a biological and taxonomic perspective, "chishanoki" usually refers to a plant belonging to the Boraginaceae family. This plant is also known as "kakinokidamashi" and its scientific name is Ehretia acuminata var. obovata.

As can be seen from its classification, this Styrax japonica is a completely different species from Styrax japonica, and they have almost no common features. If anything, the only similarity is that both have white flowers, but Styrax japonica clearly has smaller flowers, more flowers per inflorescence, and a larger corolla.

Furthermore, while the leaves of the Japanese snowbell tree (Styrax japonica) have serrated edges, those of the Japanese laurel (Chisha kiusiana) have entire margins without serrations.

This raises the question of why the Styrax japonica and the Chishanoki tree share the same name, but to put it simply, it seems to be a coincidence.

The alternative name for Styrax japonica, Chishanoki, is derived from the Japanese dialect name "Chinai" in the Chugoku region. Chinai is said to mean Chinari (meaning "milk-bearing"), referring to the appearance of the tree bearing abundant fruit, and it is believed that Chinari was corrupted into Chishanoki (Fukatsu and Kobayashi, 1993).

On the other hand, the name of the Boraginaceae tree, *Lactuca sativa*, is said to derive from the fact that the taste of its young leaves is similar to that of lettuce (*Lactuca sativa *).

Based on the above, let's make sure not to confuse them.

What are the differences between Styrax japonica, Deutzia crenata, Symplocos chinensis, and Stewartia pseudocamellia?

It seems that people often search for the differences between Styrax japonica, Deutzia crenata, Symplocos chinensis, and Stewartia pseudocamellia along with Styrax japonica. This is probably because their white flowers look somewhat similar.

However, if you look closely, you'll quickly notice the difference.

Stewartia monadelpha, also known as Japanese stewartia, belongs to the Camellia family. Its most distinctive feature is that its stamens are significantly more numerous and larger than those of other species, and the filaments fuse together in the middle to form a tube. This feature is not seen in the other four species.

Furthermore, Symplocos myrtacea belongs to the Symplocaceae family, and its stamens are longer than those of other species, protruding significantly from the petals (or corolla lobes). This is also not seen in the other four species.

Deutzia crenata belongs to the Hydrangeaceae family, and among them it may be said to be the most similar to Styrax japonica. However, unlike Styrax japonica, its petals do not open straight down, but rather open to the side or diagonally downwards, and it can be distinguished by the dense hairs on its calyx.

What are the differences between Deutzia, Deutzia crenata, and Deutzia gracilis? We'll explain how to distinguish between similar species! Could Deutzia be the origin of hedges?

Deutzia, Deutzia gracilis, and Deutzia crenata all belong to the Deutzia genus of the Hydrangeaceae family. It is believed that their name, "Utsugi" (hollow tree), comes from the fact that, except for the young branches, the inside of the branches is hollow. In Japan, they have a history of being planted as a guide for rice planting, and are also said to be the origin of hedges...

ecological-information.com

There are other differences in leaf shape as well, but we will omit the detailed differences here. Please refer to the photos.

References

Hayashi, Masayuki. 2019. Tree Leaves: Expanded and Revised Edition - Identifying 1300 Species Through Real-Life Scans. Yama-kei Publishers, Tokyo. 824pp. ISBN: 9784635070447

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

Ohashi, Hiroyoshi; Kadota, Yuichi; Murata, Hitoshi; Yonekura, Koji; and Kihara, Hiroshi. 2017. Wild Plants of Japan (Revised New Edition, Vol. 4 Malvaceae to Apocynaceae). Heibonsha, Tokyo. 608pp. ISBN: 9784582535341

RBG Kew. 2023. 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/

Fukatsu, Tadashi & Kobayashi, Yoshio. 1993. The Origin of Tree Names. Tokyo Shoseki, Tokyo. 290pp. ISBN: 9784487722310

Vinca, climbing periwinkle, and dwarf periwinkle all belong to the Apocynaceae family and are cultivated for ornamental purposes in Japan, being commonly seen even in urban areas. They are popular for their interesting fused petals with five-lobed, propeller-like tips, but their names are similar, and the flowers of climbing periwinkle and dwarf periwinkle are almost identical, making them difficult to distinguish . The main differences between vinca, climbing periwinkle, and dwarf periwinkle can be easily distinguished by the stem structure and flower color. However, climbing periwinkle and dwarf periwinkle are quite similar. They are often collectively called "vinca," and their flowers are practically identical. While there are some differences in size, checking the leaf shape and the hairs on the calyx is the most accurate way to distinguish them. When observing them, be sure to record these features as well as the flowers. This article will explain the classification of periwinkle, climbing periwinkle, and dwarf periwinkle.

What are periwinkle, climbing periwinkle, and dwarf climbing periwinkle?

Catharanthus roseus, also known as periwinkle, is an annual plant native to Madagascar in Africa, which has been cultivated worldwide and has naturalized in tropical regions (RBG Kew, 2023). It is also cultivated in Japan for ornamental purposes.

Vinca major, also known as climbing periwinkle, is a perennial plant native to southern Europe (France, Italy, Albania, Bulgaria), the Middle East (Turkey, Lebanon, Syria), and the Caucasus. It has been cultivated and naturalized throughout the world. It is also cultivated in Japan for ornamental purposes.

Vinca minor, also known as dwarf periwinkle, is a perennial plant native to Europe and the Caucasus, which has naturalized after being cultivated worldwide. It is also cultivated in Japan for ornamental purposes.

All of these plants belong to the Apocynaceae family and are cultivated in Japan for ornamental purposes, and are commonly seen in urban areas. Their most distinctive feature is that they produce fused petals with five propeller-shaped lobes at the tip, a characteristic common to the Apocynaceae family. In addition to being easy to cultivate, the fact that they produce such interesting flowers is likely one of the reasons for their popularity.

However, these three species have similar names, and the flowers of Vinca minor and Vinca minor are almost identical, making them difficult to distinguish. In horticulture, they are often collectively referred to by their scientific name, "Vinca." As a result, the existence of the plant known as "Vinca minor" is often not even recognized.

What are the differences between periwinkle, climbing periwinkle, and dwarf climbing periwinkle?

While periwinkle belongs to the genus Vinca within the family Apocynaceae, climbing periwinkle and dwarf climbing periwinkle belong to the genus Vinca (Wu & Raven, 1995).

Therefore, the differences between periwinkle, climbing periwinkle, and dwarf periwinkle are quite clear.

Specifically, while periwinkle lacks stolons, climbing periwinkle and dwarf periwinkle have them.

A creeping stem is a stem that emerges from the base of a plant and grows horizontally along the ground, and it has the characteristic of being a "vine," as its Japanese name suggests. If you see a stem creeping along the ground, it is either Vinca minor or Vinca minor.

Furthermore, regarding flower color, while the corolla of the periwinkle is pink or white, the corolla of the climbing periwinkle and dwarf periwinkle is purple. I don't think there are many exceptions.

Distinguishing between Vinca minor and Vinca minor is difficult, but you can find definitive differences mainly in the shape of the leaves and the hairs on the calyx.

Regarding the leaves, the base of the leaves of Vinca minor is truncate to heart-shaped, while that of Vinca minor is wedge-shaped. In other words, Vinca minor has more typical leaf shapes.

Regarding the calyx, *Vinca minor* has fine hairs and a thread-like tip, while *Vinca minor* is hairless and has a blunt tip. The difference is most noticeable when the flower is in bud.

Other differences include the fact that the flower stalks of Vinca minor are 3-5 cm long, while those of Vinca minor are 1-1.5 cm long, and Vinca minor has slightly more corollas. However, there is variation, so this should only be used as a general guideline.

What is the variety of periwinkle?

There are known varieties of periwinkle. 'Variegata' is almost identical to periwinkle, but its leaves have variegation and are white on the edges.

References

RBG Kew. 2023. 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/

Wu, ZY, & Raven, PH (Eds.). 1995. Flora of China (Vol. 16 Gentianaceae through Boraginaceae). Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis. 479pp. ISBN: 9780915279333

Ardisia japonica, Ardisia crenata, Ardisia japonica, and Ardisia trifoliata all belong to the genus Ardisia in the family Primulaceae. They grow wild in evergreen broad-leaved forests, but are also widely cultivated as ornamental shrubs, along with Ardisia crenata of the family Chloranthaceae, because they bear red, spherical fruits in autumn and winter. They are particularly popular in Japan. However, since the fruits of all these plants are almost identical in shape, some people may not be able to tell the difference. However, if you pay close attention to the size of the trees and the shape of the leaves, they are relatively easy to distinguish. The serrations on the leaf margins of Ardisia crenata are enlarged, forming a state called "leaf nodules," which are in symbiosis with bacteria. While it was once thought that this role was for nitrogen fixation, it is now believed that it is to supply defensive secondary metabolites and growth factors. This article will explain the classification of the genus Ardisia.

What are Ardisia japonica, Ardisia crenata, Ardisia crenata, and Citrus tachibana?

Ardisia japonica, also known as Japanese laurel, is an evergreen shrub distributed in Hokkaido (southwestern part), Honshu, Shikoku, Kyushu, and the Tokara Islands in Japan; as well as in Korea and southern China, mainly growing on the forest floor of evergreen broad-leaved forests (Kanagawa Prefecture Flora Survey Association, 2018).

Ardisia pusilla, also known as vine jasmine, is distributed in southern Hokkaido to Kyushu in Japan, as well as in Korea, China, Taiwan, the Philippines, and Thailand. It is an evergreen shrub that grows in evergreen broad-leaved forests (Hayashi, 2019).

Ardisia crenata, also known as Manryo, is an evergreen shrub distributed throughout Japan (west of the Kanto region), Shikoku, Kyushu, and the Ryukyu Islands; and East Asia, mainly growing in evergreen broad-leaved forests.

Ardisia crispa, also known as the Chinese orange tree, is an evergreen shrub distributed in Honshu (west of the Kanto region), Shikoku, Kyushu, and the Ryukyu Islands in Japan; as well as in China and Taiwan, growing in evergreen broad-leaved forests.

Both belong to the genus Ardisia in the family Primulaceae, and are evergreen shrubs that are widely cultivated for ornamental purposes, along with plants like Ardisia crenata (a member of the Chloranthaceae family), because they bear red, spherical fruits from autumn to winter. They are especially often seen at Shinto shrines and Buddhist temples.

Taxonomically, the genus Ardisia is distinguished from other genera in the Primulaceae family by its terminal or axillary inflorescence, saucer-shaped and deeply lobed corolla with spirally overlapping corolla lobes, superior ovary, and single, spherical seed.

However, distinguishing between the four types mentioned above may be difficult without close observation.

What are the differences between Ardisia japonica, Ardisia crenata, Ardisia crenata, and Citrus tachibana?

There are eight species of Ardisia genus in Japan, but this time we will focus on four of the most common species found on the mainland.

These four species are difficult to distinguish if you only look at their red, spherical fruits, but they are relatively easy to differentiate if you pay close attention to the size of the trees and the shape of the leaves (Kanagawa Prefecture Flora Survey Association, 2018; Hayashi, 2019).

First, Ardisia japonica and Ardisia crenata grow to a height of 5-30 cm, have stolons, and their above-ground parts are unbranched, with leaves arranged somewhat whorled at the top of the stem. In contrast, Ardisia crenata and Citrus tachibana grow to a height of over 30 cm, lack stolons, have upright above-ground parts, and their leaves are arranged alternately.

To put it simply, Ardisia japonica and Ardisia crenata only grow to be quite small.

Furthermore, the leaves also exhibit distinctive characteristics: Ardisia japonica and Ardisia crenata lack internal glandular dots on the leaf margins, while Ardisia crenata and Citrus tachibana also lack internal glandular dots on the leaf margins.

The term "internal glandular dots" might be confusing, but in Ardisia crenata and Citrus tachibana, you can observe tiny, dot-like holes on the leaf margins. These are the holes that are being referred to.

Regarding Ardisia japonica and Ardisia crenata, Ardisia japonica has no long hairs on its leaves and stems, its serrations are fine, and its stolons do not have leaves, while Ardisia crenata has long hairs on its leaves and stems, its serrations are coarse, and its stolons do have leaves.

The shape of the leaves makes it obvious.

Ardisia walkeri, which is distributed from southern Kanto to the Chugoku and Kyushu regions, has long hairs but many serrations.

Regarding Ardisia crenata and Citrus tachibana, Ardisia crenata has oblong leaves, a stem that branches at the top, and terminal, sessile inflorescences on the branches, while Citrus tachibana has broadly lanceolate leaves that gradually taper to a point, a stem that hardly branches, and stalked inflorescences that emerge from the leaf axils.

However, this is a strict distinction, and you don't need to look that closely to distinguish between them, as only Ardisia crenata has thick, finely serrated edges on its leaves, so you shouldn't get confused.

What kinds of varieties and cultivars are there?

Varieties and cultivars also exist for Ardisia japonica, Ardisia crenata, Ardisia crenata, and Citrus tachibana (Ohashi et al., 2017).

Ardisia japonica f. albifructa is a variety of Ardisia japonica with white fruits.

Ardisia japonica var. angusta is a variety of Ardisia japonica with narrow, oval leaves, distributed in Izu Oshima, Yakushima, and Taiwan.

Ardisia japonica var. angusta f. leucocarpa is a variety of Ardisia japonica distributed on Izu Oshima Island, characterized by its narrowly oval leaves and white fruits.

Ardisia pusilla var. liukiuensis is a variety of Ardisia pusilla distributed in Okinawa, and is generally larger, reaching a height of nearly 30 cm.

Ardisia crenata f. leucocarpa is a variety of Ardisia crenata with white fruits.

Ardisia crenata f. xanthocarpa, also known as "Kimino Manryo," is a variety of Ardisia crenata with yellow fruits.

Ardisia crispa f. leucocarpa is a variety of Ardisia crispa with white fruit.

Ardisia crispa f. xanthocarpa is a variety of Ardisia crispa with yellow fruit.

Ardisia crispa var. caducipila is a variety of Ardisia crenata that is distributed in Honshu (Wakayama Prefecture) and Kyushu (Yakushima Island) and has small bristles on the petioles and underside of the leaves when young.

Is it a lie that Ardisia crenata fixes nitrogen?

Ecologically, the genus Ardisia is known to harbor the genus Burkholderia, a type of eubacteria, on the leaf margins (Yang & Hu, 2022).

This is particularly noticeable with Ardisia crenata; the edges of its leaves are serrated and wavy, but these serrated parts become enlarged, forming what is called a "leaf nodule."

This contains Burkholderia, and this relationship is thought to be one-to-one, having co-evolved. In the case of Ardisia crenata, it contains the species Burkholderia crenata.

Previously, due to low identification accuracy, it was thought that a completely different species of bacteria was present. Because this bacteria was a nitrogen-fixing bacterium capable of utilizing nitrogen from the air, the idea that "Ardisia crenata can fix nitrogen from its leaves" was temporarily established. Since nitrogen is an essential element for protein formation, the ability to fix nitrogen is considered a special characteristic.

However, it has now been identified as belonging to the genus Burkholderia, and while some species in this genus are capable of nitrogen fixation, it has become clear that species that live in symbiosis with the genus Ardisia do not perform nitrogen fixation.

Therefore, it is believed that species in the Ardisia genus, including Ardisia crenata, are unable to fix nitrogen from their leaves.

Instead, the genus Burkholderia has been shown to supply defensive secondary metabolites and growth factors to the genus Ardisia, which cannot grow beyond the seedling stage without Burkholderia (Carlier et al., 2016).

Although they don't fix nitrogen, the genus Burkholderia is still considered essential for the genus Ardisia.

References

Carlier, A., Fehr, L., Pinto-Carbó, M., Schäberle, T., Reher, R., Dessein, S., … & Eberl, L. 2016. The genome analysis of Candidatus Burkholderia crenata reveals that secondary metabolism may be a key function of the Ardisia crenata leaf nodule symbiosis. Environmental Microbiology 18(8): 2507-2522. https://doi.org/10.1111/1462-2920.13184

Hayashi, Masayuki. 2019. Tree Leaves: Expanded and Revised Edition - Identifying 1300 Species Through Real-Life Scans. Yama-kei Publishers, Tokyo. 824pp. ISBN: 9784635070447

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

Ohashi, Hiroyoshi; Kadota, Yuichi; Murata, Hitoshi; Yonekura, Koji; and Kihara, Hiroshi. 2017. Wild Plants of Japan (Revised New Edition, Vol. 4 Malvaceae to Apocynaceae). Heibonsha, Tokyo. 608pp. ISBN: 9784582535341

Yang, CJ, & Hu, JM 2022. Molecular phylogeny of Asian Ardisia (Myrsinoideae, Primulaceae) and their leaf-nodulated endosymbionts, Burkholderia sl (Burkholderiaceae). PloS One 17(1): e0261188. https://doi.org/10.1371/journal.pone.0261188

Primroses (Primula japonica), Japanese primroses (Primula japonica), and Japanese primroses (Primula sieboldii) are all native perennial plants belonging to the Primulaceae family and Primula genus. Their flowers are similar in shape and are usually pink, leading to confusion among the three species. However, distinguishing them is relatively easy by examining the shape of their leaves. It's important to note, however, that the Primula genus includes many species, both wild and cultivated, so it's crucial not to confuse them. This article will explain the classification of Primroses, Japanese primroses, and Japanese primroses.

What are Primula japonica, Primula sieboldii, and Primula japonica?

Primula japonica, also known as the nine-petaled primrose, is a perennial herb distributed in Hokkaido, Honshu, and Shikoku in Japan, growing in wetlands in mountainous areas.

Primula sieboldii, also known as the Japanese primrose (Sakurasou), is a perennial plant found in Hokkaido, Honshu, and Shikoku in Japan; northeastern China; the Korean Peninsula; and eastern Siberia. In Japan, it is a classic horticultural plant, with hundreds of varieties developed during the Edo period. However, in modern horticulture, it is often confused with completely different species such as Primula x polyantha, Primula x juliana, and Primula malacoides, which are introduced species.

Primula kisoana, also known as Kakkosou (勝紅草), is a perennial herb distributed in Honshu, Japan (Gunma Prefecture), and grows in the undergrowth of mountain forests.

All three species belong to the genus Primula in the family Primulaceae and are native perennial herbs to Japan. Their flower shapes are similar, with a long, slender corolla that opens into five lobes at the top. They also share the characteristics of Primula species, such as erect stems and basal leaves. Therefore, distinguishing them can be difficult. All three species listed here have pink corollas.

What are the differences between Primula japonica, Primula sieboldii, and Primula japonica?

There are 14 known species of the genus Primula in Japan alone, and there are also cultivated varieties, so it is not possible to strictly introduce all the distinguishing features of all species here. However, the three species listed here are easy to distinguish (Ohashi et al., 2017; Kanagawa Prefecture Flora Survey Association, 2018). Many other species of Primula grow locally in specific regions.

First, there is a difference in that Primula japonica has no hairs on both sides of its leaves and has glandular powdery material on the underside, while Primula japonica and Primula sieboldii have hairs on both sides of their leaves and do not have glandular powdery material on the underside.

This should be obvious at a glance.

Regarding primroses and kale, the difference lies in the shape of their leaves: primroses have oval leaves with double serrations along the margins, while kale has broadly circular leaves with a heart-shaped base, shallow, irregular palmate incisions along the margins, and even finer serrations.

This is also immediately obvious. In both cases, the leaves are crucial for distinction. While there are some slight differences in the flowers, it's important to carefully record the leaves.

In addition, there is a known variety of Primula kisoana called Primula kisoana var. shikokiana, which is distributed in Tokushima, Kagawa, and Ehime prefectures in Shikoku. It grows in the undergrowth of trees in mountainous areas, and unlike the base variety, its sepals are long, measuring 1.2 to 1.5 cm, and the throat of the flower is yellowish.

References

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

Ohashi, Hiroyoshi; Kadota, Yuichi; Murata, Hitoshi; Yonekura, Koji; and Kihara, Hiroshi. 2017. Wild Plants of Japan (Revised New Edition, Vol. 4 Malvaceae to Apocynaceae). Heibonsha, Tokyo. 608pp. ISBN: 9784582535341

Rumex japonicus, Rumex longifolius, Rumex crispus, and Rumex serrata all belong to the genus Rumex in the family Polygonaceae. Originally, only Rumex japonicus was distributed in Japan, but multiple species have invaded and become extremely common weeds. They all share a preference for disturbed ground, and are often found growing together. Furthermore, the appearance of their flowers and fruits is very similar, making identification difficult without careful comparison. They can be distinguished from sorrel species by the shape of their leaves and flowers. More than 10 species of Rumex have been confirmed in Japan, and accurate identification requires a field guide, but if we limit ourselves to the four most common species, the most accurate method of identification is by the shape of the "inner perianth that encloses the fruit." The flowers are very inconspicuous and small, with no distinction between the inner perianth (petals) and outer perianth (sepals). This is because they are wind-pollinated, not pollinated by insects. After pollination, the inner perianth remains, swells and flattens, and encloses the fruit (achene). This structure allows the seeds to be carried to other locations by wind and water. However, the presence of thorns (serrations) on the inner perianth and "white, knob-like protrusions" suggests the possibility of "dispersion by attachment to animals" or "dispersion by animal feeding," although this has not been adequately researched. This article will explain the classification, pollination ecology, and seed dispersal of dock species.

What are Rumex japonicus, Rumex longifolius, Rumex crispus, and Rumex serrulata?

Rumex japonicus, also known as dock (or pygmy dock), is a common perennial herb found in Hokkaido, Honshu, Shikoku, Kyushu, and the Ryukyu Islands in Japan; as well as in Korea and China, growing in wastelands, roadsides, and fields in urban areas and around human settlements.

Rumex crispus, also known as long-leaved dock, is native to Europe and has naturalized widely throughout the Eurasian continent. It is a perennial herb that grows in wastelands and roadsides in urban areas and around human settlements.

Rumex conglomeratus, also known as "wasteland dock," is native to Europe and has naturalized widely throughout Eurasia. In Japan, it was introduced during the Meiji era and is commonly found in central Honshu, growing in wastelands and roadsides in urban areas and around human settlements.

Rumex obtusifolius, also known as Ezo dock, is native to Europe and has naturalized widely throughout the world, including Japan. It is a perennial herb that grows in wastelands and roadsides in urban areas and around human settlements.

All of these species belong to the genus Rumex in the family Polygonaceae. Originally, only Rumex japonicus was found in Japan, but now several species have invaded from Eurasia and have become extremely common weeds. They also share a preference for disturbed soil, and are often found growing together. Furthermore, their flowers and fruits look very similar. Therefore, they may be easily confused if not carefully observed.

What is the difference between dock and sorrel?

Before considering these four species, it's important to note that the genus Rumex also includes other species besides the common dock (Rumex acetosa) and the dwarf sorrel (Rumex acetosella). What are the differences between these two species?

First, there is a difference between dock species (Rumex serrata) and sorrel species (Rumex acetosa). In other words, all dock species have "hermaphrodite flowers" that have both stamens and pistils, but sorrel species have two types: individuals with "male flowers" that have only stamens (male plants) and individuals with "female flowers" that have only pistils (female plants).

The female flowers of this sorrel species are very red and conspicuous, so you can spot the red inflorescence of sorrel species even from a distance. This is not the case with dock species.

In terms of leaf morphology, dock species have wedge-shaped, rounded, or heart-shaped leaf bases, while sorrel species have scaly or lanceolate leaf bases. This difference may be useful when observing plants outside of their flowering season.

In addition, the Japanese name for sorrel (suiba) is said to be "suiba" (sour leaf), derived from its sour taste. This sourness comes from oxalic acid, which is also found in dock plants, but sorrel seems to be more sour, possibly because it contains more oxalic acid. According to someone who actually compared the two, "suiba is clearly more sour" (Ayumin, 2021). Therefore, this can be used to distinguish them, but it seems that no one has confirmed whether all dock plants are not sour.

What are the differences between *Rumex japonicus*, *Rumex longifolius*, *Rumex serrata*, and *Rumex japonica*?

More than 10 species of the genus Rumex have been identified in Japan, including the sorrel species mentioned earlier, making accurate identification difficult without consulting a field guide. However, the four species listed at the beginning are the most commonly found in urban areas and are frequently encountered. Therefore, this section will explain how to distinguish between these four species. For those who want to accurately distinguish all species, please refer to Ohashi et al. (2017) or the Kanagawa Prefectural Flora Survey Association (2018).

Firstly, in Rumex japonicus, the edges of the inner perianth surrounding the fruit have prominent thorns, whereas in Rumex crispus, Rumex longifolius, and Rumex serrata, the edges of the inner perianth surrounding the fruit are entire or have only shallow serrations.

The "inner perianth surrounding the fruit" is a structure unique to the Rumex genus. It is the inner perianth that was present between the flowers, which remains after flowering and becomes thinner, with a white, knob-like projection attached to the center. This is quite noticeable even from a distance.

Regarding the remaining three species, in *Rumex crispus*, the flowers and fruits are spaced apart and arranged in whorls, so the inflorescence appears sparse, and the inflorescence and fruit clusters have bracts. In contrast, in *Rumex rotundifolia* and *Rumex longifolia*, although the flowers and fruits are also arranged in whorls, they are spaced closely together, forming a large panicle inflorescence overall, and the inflorescence and fruit clusters lack bracts.

Regarding dock (Rumex japonicus) and long-leaved dock (Rumex crispus), the difference is that in dock, the inner perianth surrounding the fruit has low serrations along the edge and a slightly pointed tip, while in long-leaved dock, the inner perianth has an entire margin with a rounded tip.

In addition, it may be possible to distinguish them based on the leaves alone, but this would be complicated due to differences between stem leaves and basal leaves, so we will omit that here. The period when the inner perianth is present is limited, but it would be desirable to confirm this point if possible.

Furthermore, these four species prefer similar environments and coexist, leading to the observation of many hybrids. If fruiting is infrequent and intermediate characteristics are present, it may be necessary to consider the possibility of a hybrid.

What is the structure of a flower?

The flowers of the Rumex genus have a similar structure to typical flowers. However, they are very inconspicuous and small, and the calyx and petals are almost indistinguishable in appearance. For this reason, the part corresponding to the calyx is often called the "outer perianth," and the part corresponding to the petals is called the "inner perianth."

Dock (Rumex rotundifolia) flowers from June to August (Wu et al., 2003). Its inflorescence is a panicle, densely arranged in multiple whorls. It is monoecious, with both hermaphroditic and female flowers. The pedicels are slender, with nodes located below the middle and clearly defined. Each flower consists of three outer perianth segments, three inner perianth segments, six stamens, and one pistil.

Rumex rotundifolia flowers from June to August, with flowers borne in long racemes that are densely arranged in multiple whorls. It is monoecious, with both hermaphroditic and female flowers. Each flower consists of three outer perianth segments, three inner perianth segments, six stamens, and one pistil. The pistil has three styles, and the stigma is finely divided.

Rumex crispus flowers from June to July. Its flower stalks are branched with long internodes, and the flowers are densely arranged in whorls at each node. The pedicels are 1-4 (up to 5) mm long. The flowers are small, with the inner perianth measuring 2-3 mm in length and 1-1.6 (up to 2) mm in width.

Rumex japonicus flowers from June to August. The flowers are borne in long racemes, arranged in whorls with spacing between tiers. It is monoecious, with both hermaphroditic and female flowers. Each flower consists of 6 perianth segments (sepals), 6 stamens, and 1 pistil.

How is pollination done?

It is known that flowers of the Rumex genus, including sorrel species, are commonly pollinated by wind (Wagatsuma et al., 1974; Zaller, 2004; CABI, 2021). In fact, airborne pollen has been discovered in Japanese research. Morphologically, the indistinguishable nature of the sepals and petals indicates a lack of appeal to insects, and the absence of nectar secretion suggests that there is no need to attract insects.

Among wind-pollinated flowers, it is classified as a "pendulous type," and because the flower stalks extend downwards, the flowers appear to droop and are easily swayed by the wind (Utsumi, 2002).

What is the structure of the fruit?

The fruits of the Rumex genus are all achenes. An achene is a fruit with a hard, membranous pericarp that dries when ripe and contains one seed in each chamber. However, as mentioned above, the three inner perianth segments enlarge during fruiting and enclose the fruit, so the shape of the fruit cannot be seen from the outside (Iwase et al., 2021). In addition, some species have "white, knob-like projections (tubercles)" on the inner perianth segments, which is also a distinctive feature, but some species, such as Rumex acetosa and Rumex chinensis, do not have these. Only one fruit (achene) is enclosed within the three inner perianth segments.

The three inner perianth segments of the dock are broadly heart-shaped, 4-5 mm long and 5-6 mm wide. All inner perianth segments have white, knob-like projections, distinct reticulate venation, a heart-shaped base, irregularly toothed margins, and an acute apex, with the teeth measuring 0.3-0.5 mm in height. The inner achenes are dark brown, glossy, broadly ovate, sharply triangular, about 2.5 mm long, with a narrow base and an acute apex.

The three inner perianth segments of *Rumex japonicus* are broadly ovate, entire, with rounded tips and a knob-like projection in the center. The size of the knob-like projection varies. The inside of the inner perianth is slightly concave, but otherwise almost flat. The achene is three-angled and brownish-red.

The three inner perianth segments of *Rumex crispus* are oblong-ovate, entire, and the central knob-like projection is often reddish. The achenes are the smallest among the *Rumex* species, measuring 1.5–2 mm in length and 1–1.6 (2) mm in width, and are dark brown.

The three inner perianth segments of *Rumex japonicus* are ovate, with a slightly elongated, pointed tip, long projections along the edges, and a knob-like projection in the center. The projections along the edges are often sparse, and the knob-like projection is usually red. The achenes are 2–2.7 mm long and 1.2–1.7 mm wide, triangular in shape, and brown to reddish-brown in color.

What are the methods for seed dispersal? There are many methods besides "wind dispersal"!

The most common seed dispersal method for the Rumex genus is wind dispersal (CABI, 2021). The three flattened inner perianth segments are carried away by the wind, spreading to various locations. This is the same method used for pollen dispersal, and by not relying on luck factors like insects or animals, it can spread very effectively in open, disturbed areas. The flattened structure is also well-suited to floating on water, so water dispersal also occurs.

However, the presence of various appendages suggests that dispersal is not simply wind-based. For example, in some species, including Rumex japonicus, the inner perianth segments have serrations. This is thought to allow them to adhere to the fur and feathers of animals (mammals and birds), including humans, enabling them to travel long distances (CABI, 2021). In other words, they act as "burrs" and disperse by attaching to animals. However, the specific animals involved are unclear. Their shape makes it seem unlikely they would adhere to human clothing.

In addition, while many species exhibit "white, knob-like protrusions" on the inner perianth segments, some species lack them. What role do these protrusions play? It seems that lighter protrusions would be preferable if they were to be carried by wind or water.

I couldn't find any proper research on this. I think there are several different ideas about this role.

Firstly, after being carried away by wind and water, seeds accumulate in the soil, but this is not always a suitable environment for their survival. Therefore, it is already known that they wait underground until they are ready to germinate, forming a "seed bank" (CABI, 2021). In one study, 83% of Rumex japonicus seeds remained viable after being buried for 21 years.

Therefore, it may exist to supply nutrients to the seeds while it is in existence as a seed bank. However, structurally, the protrusions do not appear to be in contact with the seeds, so it is unclear whether this is possible, and it is questionable whether dormancy is impossible without such a structure.

Secondly, it may serve the purpose of providing nutrients to animals that eat the seeds. In fact, it is known that the seeds are eaten by mammals such as birds and cows (CABI, 2021; Bhandari & Park, 2022). This is called "animal dispersal." In the case of birds, it is said that they will eat the fruits of the dock family if there are no other good food sources. It is also known that the ingested seeds are difficult to digest and can be dispersed through feces. Based on this fact, it is natural to think that there is something about the fruit that makes animals think, "It's delicious!"

The third reason is that it's a structure for buoyancy. The cross-section of the white, knob-like protrusions looks like cork. Perhaps having such a structure actually makes the seeds float more easily.

It is thought that one or more of these roles exist, but this has not been verified at all. They may have a great many seed dispersal methods, but which one they primarily rely on likely varies depending on the species.

References

Ayumin. [Ayumin's Weed Cafe]. (January 20, 2021). Thorough Comparison! Sorrel vs. Dock ① ~Comparing raw and boiled versions by color~ [Video]. YouTube. https://www.youtube.com/watch?v=cTcnUJvmrkQ

Bhandari, GS, & Park, CW (2022). Molecular evidence for natural hybridization between Rumex crispus and R. obtusifolius (Polygonaceae) in Korea. Scientific Reports, 12 (1), 5423. https://doi.org/10.1038/s41598-022-09292-9

CABI. (2021). Rumex obtusifolius (broad-leaved dock). CABI Compendium. https://doi.org/10.1079/cabicompendium.48064

Iwase, T., Kawana, K., & Iijima, K. (2021). Weeds in schoolyards (revised edition). National Rural Education Association. ISBN: 9784881371992

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

Ohashi, Hiroyoshi; Kadota, Yuichi; Murata, Hitoshi; Yonekura, Koji; and Kihara, Hiroshi. (2017). Wild Plants of Japan (Revised New Edition, Vol. 4: Malvaceae to Apocynaceae). Heibonsha. ISBN: 9784582535341

Utsumi, Shusaku. (2002). Why are flowers beautiful? 1. Insects and pollination. Research Bulletin of the Faculty of Education, Chiba University, 50, 441-448. ISSN: 1348-2084, https://opac.ll.chiba-u.jp/da/curator/900026751/

Yoshinori Wagatsuma, Ryuji Matsuyama, Mikiya Sato, Koji Ito, Tamiko Mizutani, and Yoko Fujisaki. (1974). Rumex acetosa and dock pollen allergy (hay fever). Allergy, 23(3), 245-246. https://doi.org/10.15036/arerugi.23.245_2

Wu, ZY, Raven, PH, & Hong, DY (Eds.). (2003). Flora of China (Vol. 5 Ulmaceae through Basellaceae). Science Press, and Missouri Botanical Garden Press. ISBN: 9781935641056

Zaller, JG (2004). Ecology and non-chemical control of Rumex crispus and R. obtusifolius (Polygonaceae): a review. Weed Research, 44 (6), 414-432. https://doi.org/10.1111/j.1365-3180.2004.00416.x

Oleander is a cultivated tree commonly found in parks and along streets throughout Japan, but it originally thrives in the Mediterranean and Southeast Asia. While there are various theories, it is said that 5 to 15 leaves are a lethal dose, and although extremely rare, there have been reports of poisoning in Japan. The smoke from burning oleander has also been proven to be toxic. Historically, there are legends of people being poisoned or dying from using oleander branches as skewers. On the other hand, in Hiroshima, it is considered a symbol of peace and reconstruction as it was one of the first flowers to bloom after the atomic bombing. Despite its strict nature, the oleander's hardiness stems from its adaptation to the Mediterranean climate, and it possesses many interesting ecological characteristics . There is a hypothesis that its flowers may mimic a species of rhododendron, a relict species from the Cenozoic Tertiary period, whose habitats do not currently overlap. This article will explain the classification, toxicity, history, pollination ecology, and seed dispersal of the oleander.

A plant that looks like a cross between bamboo and peach? A hugely popular plant for landscaping all over the world.

Nerium oleander (in the broad sense) is native to the Mediterranean region, including North Africa, Southern Europe, and Southeast Asia. In nature, it is an evergreen shrub that mainly inhabits waterways, such as forests and shrublands along riverbanks and streams, rocky and gravelly areas, intermittent waterways between damp canyons and slopes, and near springs in arid regions (Vélez-Gavilán, 2021). It belongs to the family Apocynaceae. The genus name Nerium comes from the Greek word for "moist" (Tanaka, 2011). Because it requires sufficient moisture to germinate, its distribution in the wild is limited (Herrera, 1991).

However, this may give you the impression that it is quite different from the habitat you might imagine in Japan, and you might wonder if it can be commonly found in dry areas. This is probably because, under cultivation, it is propagated by cuttings, so it does not require water for germination.

They are adapted to the Mediterranean climate and make up sclerophyll forests, including olive trees, cork oaks, and carob (Herrera, 1991). Such plants can adapt not only to drought but also to various adverse conditions such as frequent wildfires, heavy rains, and nutrient deficiencies.

The oleander commonly seen in Japan is the introduced species Nerium oleander var. indicum, which is believed to be native to India (Hirano, 1997). However, there is little information available from overseas regarding N. oleander var. indicum, and the exact distribution area of this variety is unknown. It is possible that this classification is not commonly used globally.

It is resistant to pollution and drought, and is now planted as a garden tree and street tree all over the world, including Japan, and can be seen even in cities.

The Japanese name is derived from the Chinese name "Jiaozhutao," which is said to be because it has slender leaves like bamboo and flowers like peaches (Tsujii, 2006; Tanaka, 2011). The leaves do not have parallel veins like bamboo, and the flowers do not look like those of the rose family like peaches, but perhaps that is how it appeared to the Chinese from a distance.

Oleander leaves adapted to Mediterranean climate

Oleander leaves are long, slender, glossy, and oblong, with thick, pointed ends. Do these narrow leaves serve any adaptive purpose?

In Mediterranean climates, while there is a reasonable amount of annual rainfall, summers are dry and winters are not particularly cold. Therefore, because water conditions are not ideal during the optimal growing season, the leaves need to be small, stiff, and drought-tolerant. This is thought to be the reason for these characteristics (Herrera, 1991). This is a characteristic of sclerophyllous trees, similar to that of olive trees.

This likely explains its characteristic resistance to dryness.

What is the difference between oleander and European oleander?

In Japan, only one species, Nerium oleander (in the broad sense), is found, and there are no similar species, but there are two varieties: Nerium oleander (in the narrow sense) and Nerium oleander (European oleander).

The difference is that in oleander (in the narrow sense), *Nerium oleander var. indicum *, the corolla appendages are deeply divided into 4 to 7 lobes and are fragrant, while in European oleander (* Nerium oleander var. oleander *), the corolla appendages are deeply divided into 3 to 4 lobes and are not fragrant (Kanagawa Prefecture Flora Survey Association, 2018). European oleander is rarely cultivated. However, this distinction is not commonly made overseas.

Furthermore, varieties with double flowers are treated as a separate cultivar called * Nerium oleander var. indicum 'Plenum'*.

The variety called Nerium oleander var. indicum 'Variegatum' has double flowers and variegated leaves.

Beware of cardiac glycosides, the toxic components of oleander.

Oleander contains several toxic compounds, including oleandrin, oleandrigenin, and other cardiac glycosides, in all parts of the plant, including leaves, flowers, roots, and stems (Farkhondeh et al., 2020). Oleander with red flowers during its flowering season produces more cardiac glycosides than shrubs with white flowers. There have been reports of poisoning symptoms and even death in humans and livestock after ingestion.

The symptoms are similar to those of digitalis poisoning, with nausea and vomiting (100%), limb weakness (84%), fatigue (83%), diarrhea (77%), non-rotational vertigo (66%), and abdominal pain (57%) occurring (Kadota et al., 2012). The mortality rate is said to be 4-10%.

Regarding toxicity, reports indicate that the oral lethal dose of oleander in adults is equivalent to 5 to 15 leaves, but there are also records of even a single green leaf being lethal, and there is no established consensus (Farkhondeh et al., 2020; Kobe et al., 2020). Furthermore, some reports suggest there is no correlation between the amount ingested and the severity of poisoning, making it difficult to estimate the severity based solely on the amount ingested.

Actual cases in Japan are extremely rare, but there have been reports of fatalities. Other known cases include poisoning from ingesting dried oleander leaves (Kadota et al., 2012), poisoning from eating oleander leaves growing in one's own garden for the purpose of self-injury (Kobe et al., 2020), and poisoning from eating oleander leaves planted on school grounds, believing them to be edible (Asahi Shimbun, 2017).

While historical legends mention poisoning from the branches, most reported cases in current medical records appear to be from the leaves.

Although oleander is planted in many places, cases of poisoning are rare, so it may not be considered particularly dangerous compared to other poisonous plants. However, you should absolutely avoid ingesting it or consuming food that has come into direct contact with oleander.

Furthermore, the idea that oleander's toxins are released into the atmosphere when its branches are burned has spread on the internet, and while it may sound like a lie, a paper published in 2011 (Senthilkumaran et al., 2011) actually details a case in India where a farming family suffered poisoning symptoms after burning branches indoors without proper ventilation, providing medical backing for this claim. Therefore, while the smoke itself may not be immediately lethal, burning oleander in an environment where smoke is inhaled is strictly prohibited.

Although few animals eat oleander due to its toxic substances, in Japan, the oleander hawk moth (Daphnis nerii), oleander aphid (Aphis nerii), and white-spotted moth (Glyphodes sp.) can be found, while in Africa, hyraxes and gazelles eat it (Herrera, 1991). Wild animals have formidable defenses.

Even Alexander the Great was troubled by oleanders...?

Oleander has a history of cultivation dating back thousands of years, originating in ancient civilizations along the Mediterranean coast.

There are several historical anecdotes regarding the poisonous nature of oleander.

There is a legend that Alexander the Great of Macedon lost many soldiers because he used oleander branches as skewers to roast meat (Fuller & McClintock, 1988; Uematsu, 2000). A similar legend exists about Napoleon's army.

In recent years, in 1975 in France, seven men and women died when oleander was used in a barbecue, and in a similar case in Australia, 10 out of 11 people died (Saito, 2021).

It is believed that the plant arrived in Japan via China during the mid-Edo period, either during the Kyoho era (1716-1736) or the Kansei era (1789-1801) (Tsujii, 2006; Tanaka, 2011).

During the Satsuma Rebellion of 1877 (Meiji 10), there are reports of soldiers of the government army using broken branches as chopsticks and suffering poisoning (Tsujii, 2006; Hakugaku Kodawari Club, 2007; Tanaka, 2012). Similar incidents are said to have occurred among Japanese troops stationed in the South Pacific during World War II (Uematsu, 2000).

Regarding the historical examples, the author is generally based on hearsay and has not been able to verify any direct historical sources, so it is unclear whether they are historical facts. However, these are episodes that make you think that they could actually have happened.

Although there are many negative stories associated with it, in Hiroshima Prefecture, it was one of the first flowers to bloom after the atomic bombing during World War II due to its resilience to drought and air pollution, and it was designated as the official flower of Hiroshima City as a symbol of reconstruction (Saito, 2021).

The mystery of the oleander flower that no one ever visits

In tropical regions, the flowers bloom almost all year round, but in Japan, they bloom during the summer months, from June to September (Tsujii, 2006). The petals are tubular at the base, flatten out at the tip, and divide into five petals, each curved like a propeller (Hirano, 1997). Wild specimens have pale pink flowers, but there are many cultivated varieties with red, yellow, and white flowers, and the double-flowered variety is called Yaekoryukuto.

In Japan, there are few suitable pollinators, so successful pollination and fruit production are rare. Furthermore, under cultivation, it is propagated vegetatively through cuttings. Therefore, it can be said that the flowers are not very useful under cultivation. However, this is only true under cultivation conditions, so such occurrences are possible.

However, oleanders, including wild specimens, do not secrete nectar! This makes it seem as though the flowers serve no purpose at all. What is the point of them blooming?

While this topic is rarely studied in Japanese literature, it has been extensively researched in Spain, where it grows naturally (Herrera, 1991).

According to the research, oleander flowers seem to be successfully pollinated by deceiving insects. In other words, they mimic other nectar-producing flowers. By doing so, they succeed in pollination without expending energy on secreting nectar.

Oleander employs various strategies to deceive insects. For starters, each flower is quite large, and numerous flowers are present in the inflorescence despite their relative value to insects. While less common in wild varieties, they also have a fragrance, and unfertilized flowers can bloom for up to a week.

The appendages to the corolla (the frilly parts in the center) are also thought to be mimicry of stamens. Of course, oleanders do have their own stamens, but these appendages make it appear as if there are many more stamens and pollen.

Oleander does have pollen, so it's not entirely worthless to insects. However, it produces less pollen than other flowers, and considering the reward for the effort insects put in, it doesn't seem to be a very good food source.

This pollen is held together by an adhesive substance, which plays a role in attaching a large amount of pollen at once to insects that are occasionally tricked into coming to it.

Even a life of deception isn't easy? The struggles of the oleander.

After hearing all this, you might think that oleander must be making a profit by "cheating."

However, the same Spanish researcher observed the area for two years and found only eight instances of insect visits. Specifically, there were three instances of a bumblebee species, Xylocopa violacea, two instances of a species of pygmy bee, two instances of a bumblebee species, Bombus lucorum, and one instance of a species of callifly. It appears that bees are the main carriers of pollen, but their numbers are extremely small.

Of course, there's a possibility that the survey is insufficient, or that the survey is biased towards daytime, meaning that moths like hawk moths might be visiting at night. However, this doesn't mean that pollination is occurring adequately. Why is this happening?

This is thought to be because there are no plants with flowers that resemble oleanders to mimic them in the oleander's habitat (in this case, Spain). If there is no model that actually secretes nectar, insects will learn that it is a fake, and the likelihood of pollination will decrease.

If that's the case, the mystery deepens even further. Why does the oleander mimic a flower that doesn't exist?

While there's no scientific evidence to support this, an interesting hypothesis has been proposed: that the flowers mimic those of extinct plant species.

In Spain, you can find Rhododendron ponticum, an extremely rare species of rhododendron (Ericaceae family) that is a relict species from the Tertiary period of the Cenozoic era. Rhododendron ponticum has large, pink flowers that grow along riverbanks. It is possible that oleander evolved to mimic Rhododendron ponticum during a time when it was widely distributed. However, now that Rhododendron ponticum has narrowed its distribution area, only oleander remains, and it may be barely surviving as a result.

However, this hypothesis is biased towards observations in Spain. Further research is needed to determine what insects visit the Mediterranean and Southeast Asia, and whether there are any model species that mimic the insect. In fact, there are known cases where no model species exist, such as with the Bletilla striata, so it is interesting to consider the situation with the oleander.

What species resembles the Bletilla striata (purple orchid)? Recent research has revealed that the flowers not only deceive bees, but also utilize male bees for courtship!

Bletilla striata is a perennial plant naturally distributed from Honshu to Okinawa in Japan, but wild specimens are classified as near-threatened. On the other hand, it's also a popular ornamental plant, and can be seen in almost every town. While it was once thought that the wild population in Japan consisted of escaped cultivated plants, it is now believed that the wild population is...

ecological-information.com

Incidentally, plumeria (Indian jasmine), also belonging to the Apocynaceae family, does not secrete nectar. However, it doesn't deceive bees; instead, it releases a large amount of scent to deceive hawk moths. Although they belong to the same family and share some commonalities, they have different ecological characteristics. This is another interesting example.

There are differences between plumeria and Indian jasmine! We'll explain how to distinguish between similar species! When did it arrive in Hawaii? Is it poisonous? Were the flower's flashy colors and scent an evolutionary adaptation to deceive moths?!

Plumeria is a popular garden plant known for its vibrant, large flowers and fragrance, symbolizing the tropics. However, it is also known as Indian jasmine. The terms "plumeria" and "Indian jasmine" may have different meanings. In Japan, "Indian jasmine" often refers to a single, common variety...

ecological-information.com

The fruit waits for the rainy season to release its seeds all at once.

The fruit is a long, slender sac that splits open vertically when ripe, releasing seeds covered in long, brown, downy hairs (Hirano, 1997).

The seeds are covered in long hairs and are thought to be dispersed mainly by wind, but because they descend relatively quickly and do not fall from very high places, they end up landing very close to the parent plant (Herrera, 1991).

You might think that this would prevent them from expanding their habitat, but since oleanders can only survive in environments near waterways, there's no need for them to expand their habitat far away. In fact, it's advantageous for the seeds to grow near the parent plant.

Additionally, spraying with water from waterways is also carried out as a secondary method, but this is not considered to be of much importance.

Oleanders produce many flowers, but since most of them are for show, they don't produce many fruits. However, they do produce a large number of seeds per fruit. This is thought to be because, in the Mediterranean climate with dry summers, the fruits split open all at once when there is rainfall, releasing the seeds, and they germinate without missing the opportunity when there is water. It's a very rational design.

The oleander, which we often see planted in gardens, is a plant that has made remarkable adaptations to the Mediterranean climate. When you see one, it's fun to observe it while keeping this in mind.

References

Asahi Shimbun. December 16, 2017. Two elementary school students suffer food poisoning from oleander in Takamatsu. Asahi Shimbun. ISSN: 0917-0332, https://www.asahi.com/articles/ASKDJ4D9YKDJUBQU00N.html

Farkhondeh, T., Kianmehr, M., Kazemi, T., Samarghandian, S., & Khazdair, MR 2020. Toxicity effects of Nerium oleander, basic and clinical evidence: A comprehensive review. Human & Experimental Toxicology 39(6): 773-784. ISSN: 0960-3271, https://doi.org/10.1177/0960327120901571

Fuller, TC, McClintock, E. 1988. Poisonous Plants of California (California Natural History Guides). University of California Press, California. 384pp. ISBN: 9780520055698, https://archive.org/details/bub_gb_0-op0XwlDmQC/page/n83/mode/2up

The Erudite and Obsessive Club. 2007. Flowers and Plants: 200 Fun Facts! For example, why are there so many yellow flowers in spring? Kawade Shobo Shinsha, Tokyo. 222pp. ISBN: 9784309496504

Herrera, J. 1991. The reproductive biology of a riparian Mediterranean shrub, Nerium oleander L. (Apocynaceae). Botanical Journal of the Linnean Society 106(2): 147-172. ISSN: 0024-4074, https://doi.org/10.1111/j.1095-8339.1991.tb02289.x

Hirano, Takahisa. 1997. Tree Guidebook: Understanding the Characteristics and Uses of Trees Found in Gardens, Parks, and Wildlife. Nagaoka Shoten, Tokyo. 319pp. ISBN: 9784522215579

Kadota, N., Tabuchi, M., Shimizu, T., Higuchi, T., Tsubaki, N., and Asao, Y. 2012. A case of oleander poisoning. Japanese Journal of Intensive Care Medicine 19(4): 685-686. ISSN: 1340-7988, https://doi.org/10.3918/jsicm.19.685

Kobe, M., Nakajima, J., Murata, M., Sawada, Y., Isshiki, Y., Ichikawa, Y.,... & Oshima, K. 2020. A case of massive oleander ingestion. Kitakanto Igaku 70(4): 359-362. ISSN: 1343-2826, https://doi.org/10.2974/kmj.70.359

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

Senthilkumaran, S., Meenakshisundaram, R., Michaels, AD, & Thirumalaikolundusubramanian, P. 2011. Electrocardiographic changes during inhalational oleander toxicity. Journal of Electrocardiology 44(4): 470-472. https://doi.org/10.1016/j.jelectrocard.2010.12.002

Tsujii, Tatsuichi. 2006. Continued: Trees of Japan. Chuokoron-Shinsha, Tokyo. 230pp. ISBN: 9784121018342

Saito, Katsuhiro. 2021. The Beautiful and Terrifying World of Poisons! A Visual Encyclopedia of 200 Poisons. Shuwa System, Tokyo. 271pp. ISBN: 9784798063652

Tanaka, Kiyoshi. 2011. 100 Trees You Should Know: Trees that Support Japanese Life. Shufunotomo Co., Ltd., Tokyo. 159pp. ISBN: 9784072784976

Tanaka, Osamu. 2012. Plants are amazing: Mechanisms and ingenuity for survival. Chuokoron-Shinsha, 236pp. ISBN: 9784121021748

Uematsu, Rei. 2000. I Tried Eating Poisonous Plants. Bungei Shunju, Tokyo. 221pp. ISBN: 9784166600991

Vélez-Gavilán, J. 2021. Nerium oleander (oleander). CABI Compendium. https://doi.org/10.1079/cabicompendium.36220

Plumeria is a popular ornamental plant known for its vibrant, large flowers and fragrance, symbolizing the tropics. However, it is also known as Indian jasmine. The meanings of "plumeria" and "Indian jasmine" may differ. In Japan, "Indian jasmine" refers to a single, common species, while "plumeria" can have two meanings: it can be another name for Indian jasmine, or it can be a general term for the genus *Plumeria*. However, since only two species, Indian jasmine and round-leaved plumeria, are actually found in Japan, it's fair to consider it a general term for these two species. Indian jasmine and round-leaved plumeria can be distinguished by their leaves. While plumeria is often associated with Hawaii, it is actually native to the Americas. During the Age of Discovery, it spread throughout the world via the Spanish who came into contact with the Aztecs, and in Hawaii, it was adopted in the 19th century as a material for leis, a traditional cultural item. It is used not only for ornamental purposes but also for medicinal purposes. On the other hand, it is also toxic, and contact with its sap can cause skin irritation, so caution is necessary. Incidentally, the reason for its popularity lies in its large, vibrant flowers and pleasant fragrance, but research has shown that both originally evolved to deceive moths that visit the flowers. This article will explain the classification, history, culture, medicinal uses, toxicity, and pollination ecology of Plumeria and Indian Jasmine.

What is the difference between plumeria and Indian jasmine?

While researching plumeria, a flower with vibrant, large blossoms and a fragrant scent that symbolizes the tropics, I came across the name "Indian jasmine." Is there a difference between plumeria and Indian jasmine?

Actually, plumeria and Indian jasmine may refer to different things.

When we refer to "Indian jasmine," we are usually referring to a single, common species found in Japan.

Plumeria rubra, also known as Indian jasmine, is a deciduous, semi-succulent shrub native to Mexico, Central America, and northern South America. It is cultivated in tropical regions worldwide and has even naturalized in places like India (Rojas-Sandoval, 2020). In its native habitat, it grows in dry coastal forests and rocky areas. It is popular worldwide as an ornamental plant and is also cultivated in Japan.

On the other hand, the term "plumeria" does not refer to a single species from a biological standpoint, but rather has two possible meanings.

The first case is when it's simply listed as another name for Indian jasmine in gardening or similar contexts. In this case, you can consider "Plumeria = Indian jasmine."

The second term is sometimes used as a general term for the genus Plumeria in the family Apocynaceae. This includes Plumeria obtusa (native to the Florida Keys, southeastern Caribbean, Mexico to Guatemala), P. pudica (native to Venezuela to Panama), P. alba (native to Puerto Rico to the Windward Islands), P. clusioides (native to Cuba), P. cubensis (native to Cuba), P. ekmani (native to Cuba), P. filifolia (native to Cuba), P. montana (native to Cuba), P. tuberculata (native to the Bahamas to Hispaniola), P. subsessilis (native to Hispaniola), and P. x stenopetala (native to Hispaniola) (Perez, 2019). There are about 10 species, but classification is confusing due to significant variation in leaf shape and tree form, as well as errors in specimens. Researchers have differing opinions on the exact number of species. Identifying them by appearance alone is extremely difficult.

However, the vast majority of plumerias actually cultivated outside of the Americas, including Japan, are limited to just two species: Indian jasmine and round-leaved plumeria (Plumeria obtusa). The diversity of flower colors is the result of selective breeding. Therefore, in horticulture, it could practically be considered a general term encompassing both species. In most cases, varieties of Indian jasmine are more commonly cultivated than varieties of round-leaved plumeria.

What is the difference between Indian jasmine and Malva plumeria?

What are the differences between Indian jasmine and Malva plumeria?

This can be distinguished by its leaves (Wu & Raven, 1995).

In Indian jasmine, the leaf blade has an acute or acuminate apex, and the upper surface is dull and green, whereas in Malva plumeria, the leaf blade has a rounded apex, and the upper surface is glossy and dark green.

While this isn't a precise classification, generally speaking, Indian jasmine can have red or yellow flowers, while Malva plumeria's flowers are mostly white.

However, it has been suggested that the Malva plumeria populations commonly cultivated in Hawaii and along the Pacific coast may be hybrids (Perez, 2019).

Furthermore, the Ylist, the most reliable list of correspondences between Japanese names and scientific names, lists *Plumeria rubra * (red-flowered Indian jasmine) and *Plumeria rubra 'Acutifolia'* (Indian jasmine). It seems that this classification treats species with red flowers and pointed leaves as separate varieties from those with other flower colors but pointed leaves, but such a distinction is not made worldwide and is considered inappropriate.

How can I use plumeria?

Plumeria is cultivated worldwide as an ornamental plant for its color and fragrance, and its essential oil is used in perfumes. It is also cultivated for offerings and religious purposes. Furthermore, it is believed to have various medicinal properties and is sometimes used in traditional medicine (Criley, 2009; Perez, 2019; Bihani, 2021).

Many Japanese people associate plumeria with Hawaii. However, its country of origin is actually the Americas.

It was first cultivated in Mexico and parts of Central America, where it was highly valued by the colorful Aztec people and named tlâlcalôxôchitl (crow flower) (Criley, 2009).

A major turning point for plumeria can be said to have been the Age of Discovery. In 1522, the Spanish priest Francisco de Mendoza created a herbal encyclopedia describing the medicinal properties of local plants and how the Aztecs used them, which brought the plant to the attention of Europeans.

Later, they were brought to Japan by Spanish explorers and missionaries (the Columbus Exchange) and rapidly became popular as ornamental plants in tropical regions around the world.

By 1787, it had become widely cultivated in India and associated with temples and religious ceremonies. In India, it is known as a symbol of immortality because it can produce leaves and flowers even after being removed from the soil. When visiting Bali, Indonesia, it is planted in large numbers along roadsides and in residential areas for a similar purpose. It has also been the official flower of Palermo, Sicily, since its arrival there in the early 1800s.

The alternative name "frangipani" comes from the Marquis of the Frangipani family, a noble family that invented perfumes with the fragrance of this flower in 16th-century Italy.

In Hawaii, plumeria is used as cemetery flowers, for landscaping, and as potted plants, but it is best known for its use in leis.

Leis are believed to have been introduced by Polynesians who arrived around the 12th century, and have been used since ancient times as ornaments worn on the head, neck, and shoulders as a symbol of protection against evil, an offering, and a sign of social status.

Leis were used before plumeria was introduced, but later, around the 19th century, plumeria was incorporated as one of the plants brought in by travelers and settlers.

While tourists often purchase them as souvenirs, they were originally worn by funeral attendees and the bride and groom at weddings, symbolizing farewell (Koiso, 2022).

Tourists captivated by the fragrance and vibrant colors of Hawaiian plumeria flowers began taking cut flowers home. As tourism increased, so did interest in plumeria, and soon collectors began seeking out new varieties in the Hawaiian Islands. Plumeria associations were formed in warm regions of the United States and Australia, enjoying the enthusiastic support of collectors. In 2005, 14.6 million plumeria flowers were sold for $506,000, and tens of thousands of cuttings are exported from Hawaii every year.

In folk medicine, decoctions of the leaves, bark, and flowers have been used to treat skin diseases, sexually transmitted infections, and diarrhea, and have also been used as laxatives.

How toxic is it?

While it is a highly valued plant, it contains a milky sap common to the Apocynaceae family, and is also toxic due to the presence of various alkaloids or cardiac glycosides.

Regarding plumeria, various chemical components have been isolated and identified, including medicinal components such as iridoids, triterpenoids, flavonoids, glycosides, phenols, alkaloids, carbohydrates, amino acids, fatty acid esters, sphingolipids, lignin, monoglycerides, and coumarins (Bihani, 2021).

The white sap (milky sap) that oozes out when leaves or branches are cut is harmful and can cause rashes and skin irritation upon contact (Koiso, 2022). Although no specific cases have been confirmed, it is best to avoid intentional contact with it.

How about taking it orally?

The toxicity of oral ingestion of Indian jasmine has been investigated in experiments with mice and rats (Bihani, 2021).

In a 72-hour acute toxicity study, six groups of albino rats and albino mice (8 animals each) were orally administered methanol extract of jasmine leaves suspended in physiological saline at different concentrations (500, 750, 1000, 1250, 1500, and 2000 [mg/kg BW]). No typical symptoms such as death, convulsions, seizures, diarrhea, or increased dehydration were observed.

Based on this, the median lethal dose (_LD50) is estimated to be over 2000 [mg/kg BW]. No toxic symptoms have been observed in other experiments.

Therefore, the effects of oral ingestion are thought to be minimal, but no case studies have been conducted in humans, and there is clearly a milky sap in the Apocynaceae family, and there are no examples of it being consumed as food anywhere in the world, so you should still not intentionally put it in your mouth.

The large inflorescence and sweet fragrance are the secrets to its popularity.

The flowers are perhaps the most popular part of this plant. The flowering period varies greatly depending on the region, but it is generally long, year-round in its native Nicaragua, from March to July in Costa Rica, and from June to October in Japan. It produces inflorescences containing many flowers, and each flower is large and conspicuous. The stamens and pistils are hidden deep inside the flower and are not visible from the outside (Haber, 1984). The corolla is five-lobed, ranging in color from pink to white, with a yellow center. It emits a fragrance in the morning and evening that has been likened to roses, citrus fruits, and cinnamon (Joulain, 2008), which is another reason why it is popular with humans.

The sweet scent and showy flowers were a deception to trick insects!?

With such a sweet fragrance and showy flowers, you might imagine that many different insects visit them.

However, it has been found that the only insects that visit flowers are hawk moths, which have long mouthparts (Haber, 1984).

First, the flowers attract hawk moths by emitting a pleasant fragrance during the twilight hours when they are most active, and then they attract the moths' attention with pink to white flowers, which are said to be their preferred color. Furthermore, the yellow parts act as nectar guides, indicating the location of nectar to the hawk moths, and pollination is completed when the hawk moths thrust their bodies deep into the flowers.

But that's not all that's surprising.

This flower doesn't produce nectar. In other words, despite being shaped in a way that is so appealing to hawk moths, it's actually deceiving them into carrying its pollen.

When you consider that the sweet scent and showy flowers of the Indian jasmine, which humans adore, are actually a deception for insects, doesn't it change your perception of it?

Why hawk moths are fooled by Indian jasmine

Even with all the clever tricks in place, why are hawk moths so easily fooled? Although they are insects, hawk moths do have the ability to learn. I feel like if they could remember the shape of the flowers and where they bloom, they would stop coming immediately.

While this mystery isn't fully understood, it's believed that hawk moths learn which flowers are tasty, not by instinct, but through learning, with each generation. This is similar to how humans do. Therefore, they must first determine if a particular flower is tasty. This is also an important opportunity for the Indian jasmine. The long flowering period is thought to increase this opportunity.

Furthermore, a longer flowering period increases the chances of various types of hawk moths, which emerge at different times of the year, visiting the plant.

Furthermore, hawk moths are busy not only searching for nectar but also for mates and places to lay their eggs, so it seems inefficient for them to remember the location of each nectar source. It might be more efficient for them to find food by scent, even if they are sometimes fooled.

However, there are many flaws in their design, such as the small amount of pollen they release at once (which should limit their chances of success), and the flowers being too clustered together (making them easy for moths to remember). Perhaps the ability to deceive moths is a relatively recent development in the grand scheme of evolution. Or perhaps there are still secrets hidden within them.

We often enjoy these plants as ornamental plants without giving them much thought, but it's fun to observe them while appreciating the wonders of their evolution.

The fruit is a samara.

The fruit is rarely seen in cultivated plants, but very occasionally it produces 20 to 60 winged fruits enclosed in a cylindrical pod about 17.5 cm long. These are thought to be dispersed by wind.

References

Bihani, T. 2021. Plumeria rubra L. –A review on its ethnopharmacological, morphological, phytochemical, pharmacological and toxicological studies. Journal of Ethnopharmacology 264: 113291. https://doi.org/10.1016/j.jep.2020.113291

Criley, RA 2009. Plumeria rubra: an old ornamental, a new crop. Acta Horticulturae 813: 183-190. https://doi.org/10.17660/ActaHortic.2009.813.23

Joulain, D. 2008. Flower scents from the Pacific. Chemistry & Biodiversity 5(6): 896-909. ISSN: 1612-1872, https://doi.org/10.1002/cbdv.200890103

Haber, WA 1984. Pollination by deceit in a mass-flowering tropical tree Plumeria rubra L.(Apocynaceae). Biotropica 16(4): 269-275. ISSN: 0006-3606, https://doi.org/10.2307/2387935

Koiso, Yoshie. 2022. The New Perfume Textbook. Mynavi Publishing, Tokyo. 223pp. ISBN: 9784839979256

Perez, BK 2019. Morphological and Molecular Approaches to Disentangling the Taxonomy of Plumeria Species (Apocynaceae) [Doctoral dissertation, University of Hawai'i at Manoa]. https://www.proquest.com/openview/0354baf8a7e554801440a3bb3d22687f/1?pq-origsite=gscholar&cbl=18750&diss=y

Rojas-Sandoval, J. 2020. Plumeria rubra (red frangipani). CABI Compendium. https://doi.org/10.1079/cabicompendium.42060

Wu, ZY, & Raven, PH (Eds.). 1995. Flora of China (Vol. 16 Gentianaceae through Boraginaceae). Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis. 479pp. ISBN: 9780915279333

Trachelospermum asiaticum and Trachelospermum asiaticum are climbing plants that can be found widely in Japan, from forests to urban areas, including cultivated varieties. They can be distinguished by the hairs on the underside of their leaves and the length of their flower tubes. In Japan, they have been widely known since the time when the Kojiki was written, and it is likely that the current name is derived from Fujiwara no Teika, although it is questionable whether that anecdote is historically accurate. Did you know that Trachelospermum asiaticum is ecologically specialized in attracting hawk moths by blooming in the evening? This article will explain the classification, history, pollination ecology, and seed dispersal of Trachelospermum asiaticum and Trachelospermum asiaticum.

Climbing plants found in forests and towns

Trachelospermum asiaticum, also known as Teika-kazura, is an evergreen climbing woody plant distributed in India, Thailand, China, Korea, and Japan (Honshu to Kyushu), inhabiting evergreen forests or rocky areas (Wu & Raven, 1995; Mogi et al., 2003).

Furthermore, Trachelospermum jasminoides var. pubescens is distributed in Vietnam, China, South Korea, and Japan (from the Kinki region westward in Honshu to Okinawa), and is an evergreen climbing woody plant that inhabits sunny forest edges and shrub thickets (Wu & Raven, 1995; Kyoto Prefectural Government Environmental Department, Natural Environment Conservation Division, 2015). Therefore, Trachelospermum jasminoides is commonly found in eastern Japan, excluding cultivated varieties.

Both belong to the genus Trachelospermum in the family Apocynaceae. Their leaves are oval-shaped with entire margins, leathery in texture, and glossy on the surface. They climb up rocks and other plants.

This poisonous plant releases a white sap when its stem is broken, which can cause a rash upon contact (Satake, 2012). Additionally, although the relationship to this effect is unclear, tracheloside, a compound found in the plant, can cause diarrhea.

What are the differences between Trachelospermum asiaticum, Trachelospermum asiaticum, and Trachelospermum asiaticum?

Distinguishing between Trachelospermum asiaticum and Trachelospermum asiaticum is a little difficult, but in Trachelospermum asiaticum, the length of the broad part of the flower tube is about half the length of the narrow part, the sepals are 2-3 mm long, and the underside of the leaves is hairless or only has a few short hairs.

On the other hand, *Tetramorium sempervirens* can be distinguished by the fact that the broad part of the flower tube is almost the same length as or slightly longer than the narrow part, the sepals are 5-6 mm long, and the underside of the leaves is covered with many hairs (Kanagawa Prefecture Flora Survey Association, 2018).

The easiest way to tell them apart is to check the hairs on the underside of the leaves, but since some Trachelospermum asiaticum plants are very hairy, it's more accurate to check the flower tube. In short, Trachelospermum asiaticum has a longer flower tube. Looking at the buds is probably the easiest way to tell them apart.

It is also used as a horticultural plant, and a variety called Trachelospermum jasminoides var. pubescens 'Hatsuyukikazura' can be found. This variety is beautiful with its new leaves having irregular pink and white variegation. Considering the flower tube, it can generally be considered a variety of Trachelospermum jasminoides, but some may be Trachelospermum jasminoides (Kamimachi and Shimomura, 2009). The scientific differences between this variety and the variety called Goshikikazura were unclear in the author's research.

In addition, some horticultural specimens may contain a species called T. asiaticum (Kamimachi and Shimomura, 2009).

Among the wild species found in Japan, Trachelospermum gracilipes var. liukiuense, which is distributed south of Yakushima Island and in the Ogasawara Islands, is also known (Kamimachi and Fukui, 2015).

A plant wrapped around Princess Shikishi's tomb?

Trachelospermum asiaticum already appears as "Masakino-kazura" in the Kojiki (compiled in 712), the oldest Japanese document from the Nara period (Isono, 2009). It also appears in poems in the Manyoshu (Kawahara, 2008). It must have been a very familiar climbing plant.

The name change to "Teika-kazura" is said to be related to the Noh play "Teika".

According to the account, Princess Shikishi (a female poet from the late Heian period to the early Kamakura period, the third daughter of Emperor Go-Shirakawa) and Fujiwara no Teika (a court noble and poet from the late Heian period to the early Kamakura period, famous for selecting the "Shin Kokin Wakashū") were in a secret relationship, as Princess Shikishi, being a female member of the imperial family, could not freely pursue romantic relationships. However, Princess Shikishi remained unmarried and died first at the age of 49. Fujiwara no Teika, who continued to cherish Princess Shikishi, is said to have, after his death, become so obsessed with her that he began to cover her tomb with kudzu vines.

It is said that the spirit of Princess Shikishi conveyed this to a Buddhist monk, and after the monk helped Princess Shikishi attain Buddhahood, the plant became known to the people, and this kudzu came to be called "Teika-kazura."

This piece was composed during the Muromachi period, and the name "Teikakazura" likely originates from this. However, while there are various theories about the relationship between Fujiwara no Teika and Princess Shikishi, it is believed that it is not historically accurate (Kishibe, 2015). Nevertheless, its scandalous content stimulated the imagination of the time and seems to have given rise to various literary works. It should be understood purely as a story.

Two flower shapes that are very similar but subtly different.

Both species share the characteristic of producing fragrant white flowers in May and June, which change color from white to pale yellow. The petals are described as goblet-shaped and have a long corolla tube. The upper petal-like parts are actually fused petals that have been split into five lobes at the tip (such flowers are called sympetalous flowers), and these lobes are twisted (Mogi et al., 2003).

The flower structures of Trachelospermum asiaticum and Trachelospermum asiaticum are almost identical, but in addition to the differences in the structure of the flower tube mentioned earlier, there is a difference in that the stamens of Trachelospermum asiaticum are long enough that the anthers are visible from the outside, while those of Trachelospermum asiaticum are short enough that the anthers are not visible (Kamimachi and Shimomura, 2007).

Also, while the flower tubes of Trachelospermum asiaticum tend to be yellowish, those of Trachelospermum asiaticum are milky white.

The flowers bloom in the evening and attract hawk moths.

Trachelospermum asiaticum and Trachelospermum asiaticum begin to bloom in the evening and emit a jasmine-like fragrance. What kinds of insects do these flowers attract?

While there have been records of butterflies associated with Trachelospermum asiaticum (Nanba, 2020), it is generally believed that the long flower tube and scent attract hawk moths with long proboscises (Tanaka, 2020).

The fact that the long flower tubes limit the insects that can obtain nectar to those with long mouths, and that the flowers begin to bloom in the evening and attract moths with their scent, are characteristics often seen in flowers that attract hawk moths (pollination syndrome).

Upon examining the cross-section, it is found that there is a barb inside the tube. When a hawk moth inserts its mouthparts, it is thought that pollen from other plants attached to its mouthparts is scraped off here, and then, structurally, it comes into contact with the nearby pistil, thus facilitating pollination (Hasebe, 2016).

On the other hand, I couldn't find any research on *Trachelospermum asiaticum*, but it is generally thought to be the same as *Trachelospermum asiaticum*.

Are there differences in the insects that visit Trachelospermum asiaticum and Trachelospermum asiaticum?

It seems that the differences in ecology between Trachelospermum asiaticum and Trachelospermum asiaticum have not yet been properly studied, but it appears that there is a risk of hybridization if there is no separation of habitats.

Since there are no significant differences in the flowers themselves, it seems likely that the insects that visit them would also be largely the same. However, differences in the structure and color of the flower tube, or the length of the anthers, might explain some differences in the insects that visit them. Or perhaps there are no differences at all. I look forward to future research on this.

The fruit is carried away by the wind.

The fruit is a cylindrical follicle (Mogi et al., 2003). The seeds are linear, about 1.3 cm long, with a pappus at the tip. The fruit hangs downwards and splits open from the inside, releasing the seeds into the wind (Kobayashi, 2007 ; Kawahara, 2008). Seeds with hairs are considered a rare method of seed dispersal, found only in willows among trees in Japan (Kobayashi, 2007).

References

Isono, Naohide. 2009. List of First Encounters of Plant Names by Source. Keio University Hiyoshi Journal of Natural Science 45: 69-94. ISSN: 0911-7237, https://koara.lib.keio.ac.jp/xoonips/modules/xoonips/detail.php?koara_id=AN10079809-20090331-0069

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

Kawahara, Katsuyuki. 2008. Plants in the Manyoshu. Nanpo Shinsha, Kagoshima. 216pp. ISBN: 9784861241345

Kishibe, Makoto. 2015. Fujiwara no Teika and Princess Shikishi: A Tentative Study from the Perspective of Guardianship. Aichi University Historical Studies, Japanese History, World History, and Geography 24: 45-67. https://aichiu.repo.nii.ac.jp/records/4612

Kobayashi, Masaaki. 2007. From Flower to Seed: The Science of Seed Dispersal. National Rural Education Association, Tokyo. 247pp. ISBN: 9784881371251

Kyoto Prefectural Government, Department of Environment, Natural Environment Conservation Division. 2015. Kyoto Prefecture Red Data Book 2015 (Volume 2: Wild Plants and Fungi). Kyoto Prefectural Government, Department of Environment, Natural Environment Conservation Division, Kyoto. 611pp. https://www.pref.kyoto.jp/kankyo/rdb/index.html

Mogi, T., Takahashi, H., Katsuyama, T., & Ishii, E. 2003. Flowers Blooming on Trees: Sympetalous Flowers, Monocotyledons, Gymnosperms. Yama-kei Publishers, Tokyo. 719pp. ISBN: 9784635070058

Nanba, Yasushi. 2020. Current Status of Butterflies at Okayama Prefectural Nature Conservation Center: A Supplement to the Okayama Prefectural Nature Conservation Center Butterfly Catalog. Okayama Prefectural Nature Conservation Center Research Report 27: 43-80. ISSN: 1340-7465, https://okayama-shizenhogo-c.jp/templates/front/pdf/chosa-kenkyu/vol27/vol27_p43-80.pdf

Satake, Motoyoshi. 2012. Poisonous Plants of Japan. Gakken Educational Publishing, Tokyo. 232pp. ISBN: 9784054052697

Tanaka, Hajime. 2020. Flowers and Insects: A Collection of Discoveries of Mysterious Deception. Chikuma Shobo, Tokyo. 327pp. ISBN: 9784480436573

Hasebe, Mitsuyasu. 2016, June 12. Pollination of Trachelospermum asiaticum. Plant Development and Evolution: A Readable Plant Encyclopedia. http://www.nibb.ac.jp/plantdic/blog/?p=932

Kamimachi, Azusa & Shimomura, Takashi. 2007. An attempt at identifying several species of the genus Trachelospermum based on flower morphology. Journal of the Japanese Society of Landscape Architecture 33(1): 105-110. ISSN: 0916-7439, https://doi.org/10.7211/jjsrt.33.105

Kamimachi, Azusa & Shimomura, Takashi. 2009. Classification of horticultural varieties of the genus Trachelospermum Lem. that are distributed as plants for greening and ornamental purposes. Journal of the Japanese Society of Landscape Architecture 35(1): 75-80. ISSN: 0916-7439, https://doi.org/10.7211/jjsrt.35.75

Kamimachi, Azusa & Fukui, Wataru. 2015. Identification of Trachelospermum Lem. seedlings for landscaping distributed in Japan by PCR-RFLP method. Journal of the Japanese Society of Landscape Architecture 41(1): 151-156. ISSN: 0916-7439, https://doi.org/10.7211/jjsrt.41.151

Wu, ZY, & Raven, PH (Eds.). 1995. Flora of China (Vol. 16 Gentianaceae through Boraginaceae). Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis. 479pp. ISBN: 9780915279333

Source

This article is a significantly expanded version of one included in the following book.