Poppies, including the common poppy, the thick-leaved poppy, the common poppy, and the long-headed poppy, all belong to the genus Papaver in the family Papaveraceae and are collectively known as poppies. They are very popular as ornamental plants because they produce beautiful, large single flowers and are widely cultivated. However, they are a difficult group to identify, despite being poisonous and prone to becoming naturalized. If you limit yourself to the four species, you can distinguish them relatively easily by focusing on the condition of the stems and leaves, the presence or absence of hairs, and the shape of the fruit. The Icelandic poppy is also often confused with them, but the Icelandic poppy has no stems or leaves. Poppies are a highly addictive type of narcotic and the raw material for opium, a useful painkiller, but it is known that the very existence of poppies has spurred human evolution. They have had a significant impact on history. This article will explain the classification, morphology, evolution, and history of the genus Papaver.

What are poppies, common poppies, field poppies, and long-headed poppies?

Poppy (Papaver somniferum subsp. somniferum) is also known as the somniferum species. Native to the western Mediterranean coast of Europe and North Africa, it does not exist in the wild and is an annual plant cultivated only by humans for food and medicinal purposes (Narita et al., 1998; Kanagawa Prefectural Flora Survey Association, 2018; Samorini, 2019; RBG Kew, 2025).

Papaver somniferum subsp. setigerum, also known as the Atsumi poppy, is native to the western Mediterranean coast of Europe and North Africa. It is known as a naturalized plant and has naturalized in various parts of the world. In Japan, it was reported in 1964 on the coast of the Atsumi Peninsula in Aichi Prefecture, and it is an annual plant that sporadically occurs in urban areas and wastelands from Honshu to Kyushu (Shimizu et al., 2001). It occasionally grows in urban areas, and photos of it being taken unknowingly and posted on Instagram have made headlines, as well as seedlings being sold under the mistaken impression of the Icelandic poppy.

Poppy (Papaver rhoeas), also known as the common poppy (Papaver rhoeas), is native to Europe, North Africa, and West Asia. In Japan, it was introduced as an ornamental plant during the Edo period and has since become naturalized as an annual or biennial plant.

Papaver dubium, also known as long-fruited poppy, is native to Europe, North Africa, and West Asia. In Japan, it was first recorded in Tokyo in 1961 (Yoshikawa, 2010). Seeds have been detected in imported grains, and its distribution has rapidly expanded since the 1990s due to unintentional introduction. It is now an annual plant found in a wide area from Hokkaido to Kyushu.

All of these belong to the genus Papaver in the family Papaveraceae, and are collectively known as poppies. They are very popular as ornamental plants because they produce beautiful, large single flowers, and are widely cultivated. The fact that their stigmas have 4 to 20 radiating lobes is also an interesting feature to look at.

[Seed Plant Encyclopedia #119] What are the species of the poppy family? Photo list

The Papaveraceae family consists of herbaceous plants whose stems and leaves are often covered in a powdery white substance. Breaking the stem releases a milky white or orange-yellow sap. The leaves are alternate, pinnately lobed or pinnately compound, sometimes simple, and lack stipules. The flowers are bisexual, radially symmetrical, or bilaterally symmetrical. The sepals are 2-4 in number and separate...

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Poricidal capsules, especially those of poppies called "poppy pods," are spherical fruits that, when ripe, develop a hole at the top edge, scattering their seeds. As the metaphorical expression "like poppy seeds" suggests, the seeds are extremely small and easily dispersed by wind (wind dispersal), sometimes leading to the introduction of invasive species.

All species contain multiple alkaloids that can cause skin irritation, and it is thought that they originally evolved to produce these alkaloids for defense against predators. Among these, opioids such as morphine, codeine, and thebaine act as psychotropic drugs when ingested by humans, but are also known to be addictive. The seeds also contain papaverine, an alkaloid different from opioids.

In Japan, poppies and Papaver dubium contain morphine, codeine, and thebaine, and are therefore designated as prohibited plants under the "Opium Law." Although not mentioned here, Papaver bracteatum, a related species, also contains thebaine and is therefore designated as a prohibited plant under the "Narcotics and Psychotropic Substances Control Law."

Poppies, in particular, have been cultivated by humans in the Mediterranean since the Neolithic period and have evolved to contain high levels of morphine and codeine. One could argue that they have proliferated by "turning humans into drug addicts," or in a negative sense, "plunging them into a swamp," as exemplified by the Sino-Japanese Wars and the subsequent Qing Dynasty and the Sino-Japanese War in Manchukuo.

However, it's not all bad. Morphine is used as an analgesic in surgical anesthesia and in end-of-life care involving severe pain, and codeine is used as a cough suppressant. Furthermore, papaverine is used to treat erectile dysfunction, smooth muscle spasms, and spasms associated with gastrointestinal disorders (Ashrafi et al., 2023).

The shichimi spice blend used to udon and soba noodles contains poppy seeds (actually seeds), and it's also sometimes found sprinkled on bread (Carlin et al., 2020). It would be difficult to completely dismiss such conveniences.

This group has both significant merits and demerits, and because there are many species, each with different characteristics, and they easily become feral, accurate identification is more important than with other species.

What are the differences between poppies, common poppies, field poppies, and long-headed poppies?

The methods for distinguishing these four species are explained in detail by the Ministry of Health, Labour and Welfare and the Tokyo Metropolitan Institute of Public Health (Ministry of Health, Labour and Welfare, 2019; Tokyo Metropolitan Institute of Public Health, 2008), so here we will present a concise method of distinction based on a key (Kanagawa Prefecture Flora Survey Association, 2018).

First, there is a difference in that the base of the stem leaves of poppies and Papaver dubium clasps the stem, whereas the base of the stem leaves of common poppies and long-headed poppies do not. Also, as will be discussed later, in poppies, the immature fruit enlarges, increasing the opiate content.

The difference between poppies and Papaver dubium is that poppies have hairless stems and leaves, while Papaver dubium has stiff hairs on its stems and leaves.

Regarding the common poppy (Papaver dubium) and the long-headed poppy (Papaver rhoeas), the fruit of the common poppy is nearly spherical, while that of the long-headed poppy is oblong. This is reflected in its Japanese name, "long-fruited poppy." Also, the petals of the common poppy are larger.

Regarding flower color, poppies come in various colors such as red, white, light pink, and purple; Papaver dubium comes in red; common poppies come in white, light pink, and red; and long-headed poppies come in orange-red.

The long-headed poppy, in particular, is an extremely common species in urban areas and is dominant over other species. However, it is only ever orange-red in color and usually does not come in other colors, so it is important to be able to distinguish it properly to avoid mistaking it for another species and damaging it.

The poppy that is most often mentioned as a plant that grows wild but is prohibited from cultivation is the American poppy (Papaver dubium). This most dangerous poppy was selectively bred by humans in ancient times and has evolved to be completely specialized for opium production. Without human intervention, it only rarely escapes into the wild and cannot normally reproduce in the wild. Keep this point in mind.

What's the difference between this and the Icelandic poppy?

The Icelandic poppy is generally considered the horticultural trade name for the Siberian poppy (Oreomecon nudicaulis). It is distributed in Turkestan, China, Korea, Mongolia, and Russia (including Siberia), and in Japan, it is a perennial plant cultivated only for ornamental purposes. However, it is not heat-tolerant and is treated as an annual plant sown in autumn in Japan.

The Siberian poppy was long known by the scientific name Papaver nudicaule, but a 2022 study, based on molecular phylogenetic analysis, renamed it to the above scientific name (Banfi et al., 2022).

Furthermore, contrary to its name, it is not naturally distributed in Iceland (although it is cultivated and has become naturalized). This is a common misconception, so caution is advised.

Icelandic poppies are also difficult to identify, and there have been incidents where seedlings of Papaver dubium (a type of poppy) were mixed in with Icelandic poppies.

How can we distinguish between them? There is actually a crucial difference (Wu et al., 2008).

In Icelandic poppies, all the leaves are basal leaves, whereas in the four species of poppy (Papaver dubium, Papaver rhoeas, Papaver cornii, and Papaver dubium), there are both stem leaves and basal leaves.

In other words, Icelandic poppies do not have leaves growing from their stems.

In addition, while the Icelandic poppy is originally a perennial, the common poppy, the thick-leaved poppy, the common poppy, and the long-headed poppy are all annuals. However, in Japan, both are considered annuals.

It should be noted that the cultivated "Icelandic poppy" is not the naturally occurring Siberian poppy, but rather has a complex origin, being a hybrid of species including the Arctic poppy (Papaver radicatum).

What is the history of the poppy? Were "Devil Fruits" actually evolved by humans themselves?!

The history of poppy use is ancient. Archaeological records based on the examination of seeds found at archaeological sites suggest that Neanderthals (Homo neanderthalensis), who are considered archaic humans and who partially interbred with modern humans (Homo sapiens), may have already been using them during the Late Paleolithic period (Jesus et al., 2023). However, this "poppy" is the wild form , Papaver somniferum subsp. setigerum.

It appears that Homo sapiens were still using the poppy seed during the Early Neolithic period.

Recent research indicates that domesticated poppies (Papaver somniferum subsp. somniferum), which have undergone a level of selective breeding that can be described as an evolutionary evolutionary change, increased in number during the Late Neolithic period (3300 BC to 2300 BC), and by the Late Bronze Age (around 1050 BC to 800 BC), most of the seeds remaining in archaeological sites had been replaced by poppies.

While its seeds may have been used for food, it is believed that its primary purpose from the beginning was as a narcotic. This is because, compared to the wild type of Papaver rhoeas, its fruits are larger and contain a higher amount of opiates, which are narcotic compounds.

After a single vibrant flower blooms, the poppy produces a fruit called a perforated capsule. In cultivated poppies, this immature perforated capsule becomes remarkably enlarged, and is called a "poppy bud" (Narita et al., 1998).

When a poppy seed pod is damaged, it secretes a white milky sap (latex), which turns brown and solidifies after about 20 minutes. This solidified sap is then scraped up with a bamboo spatula or similar tool and dried to produce what is called "raw opium."

Furthermore, if water is added or the mixture is heated, it becomes "opium."

Opium contains alkaloids called opiates, the most common being morphine, codeine, and thebaine.

Opioids are chemical substances synthesized from opiates using chemical methods (sometimes the term includes opiates themselves), and include diacetylmorphine (heroin), oxycodone, fentanyl, methadone, pethidine, tramadol, buprenorphine, and pentazocine.

Opioids exert their analgesic effect by binding to opioid receptors present throughout the nervous system. They act particularly strongly in the superficial layer of the spinal cord's dorsal horn, where opioid receptors are most densely concentrated, and in the brain, they have a psychotropic effect that induces euphoria through the descending pain inhibitory system.

Opioid receptors normally bind to endogenous opioids (such as endorphins, enkephalins, dynorphins, and endomorphin synthesized by the human body), and their role is to temporarily suppress pain in emergencies. Opioids cause a malfunction in this mechanism.

However, opioids are highly addictive, and inhaling high-purity opioids can lead to opioid use disorder (opioid addiction), essentially becoming a wreck. The horrific scenes of opium dens are well-known. Synthetic and semi-synthetic opioids, thanks to their chemical structure, can easily cross the blood-brain barrier and act directly on the brain, making them even more addictive (Le Couteur & Burreson, 2003).

During the cultivation of poppies, they developed poppy flower heads and increased their opiate content. However, this meant that nutrients were diverted to the production of these substances, making it difficult for them to survive in the wild without human intervention.

In this sense, ecologically speaking, the poppy has ultimately adopted a survival strategy of "parasitizing" the human nervous system. This interpretation is quite interesting.

From a human perspective, using it as a drug seems to offer no benefits, but just as some people in Japan today use alcohol and tobacco to stabilize their mental state, in ancient times it may have been one of the things that provided a sense of liberation or creativity (Prentis, 2022). Furthermore, raw opium is of lower purity than regular opium, so it may not have had the effect of turning people into addicts.

It was used in ancient Egypt and ancient Greece even after the dawn of recorded history, and cultivation continues to this day.

Its impact on history is significant, and it was abused during the Crimean War, the American Revolutionary War, and the Franco-Prussian War, giving rise to "soldier's disease" (Funayama, 2013).

Of all the major events, the Opium Wars are undoubtedly a must-mention. This war began in 1840 when Britain forced Qing China (present-day China) to trade in opium to prevent the outflow of silver from tea purchases.

Why is black tea preferred over green tea in the UK? Are flies the only ones that visit tea plant flowers?

Tea plants contain essential nutrients like catechins and caffeine, making them an indispensable beverage in Japan, enjoyed both at home and on the go. As you may know, its origin lies in China, and it's a species not native to Japan. However, even in China, wild varieties haven't been confirmed, which is puzzling...

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Furthermore, during the period leading up to and following the Sino-Japanese War, when the Japanese Empire expanded into China, the Manchukuo Asia Development Board implemented the "Great Opium Policy," officially promoting opium use, and the situation throughout China took on the appearance of what is sometimes called the "Sino-Japanese Opium War" (Eguchi, 1988; Kumano, 2019). The manga "Manchurian Opium Squad," which is based on this incident, is very thrilling and is one of my favorite manga.

Even today, opium is used as an analgesic and cough suppressant, and is cultivated under strict control. In Afghanistan, the largest producer, 6,000 tons of opium are produced annually on 250 hectares of land (Jesus et al., 2023). The Czech Republic, France, and Russia are also known as important producing regions.

References

Ashrafi, S., Alam, S., Sultana, A., Raj, A., Emon, NU, Richi, FT, … & Kim, B. 2023. Papaverine: a miraculous alkaloid from opium and its multimedicinal application. Molecules 28(7): 3149. https://doi.org/10.3390/molecules28073149

Banfi, E., Bartolucci, F., Tison, JM, & Galasso, G. 2022. A new genus for Papaver sect. Meconella and new combinations in Roemeria (Papaveraceae) in Europe and the Mediterranean area. Natural History Sciences 9(1): 67-72. https://doi.org/10.4081/nhs.2022.556

Carlin, MG, Dean, JR, & Ames, JM 2020. Opium alkaloids in harvested and thermally processed poppy seeds. Frontiers in Chemistry 8: 737. https://doi.org/10.3389/fchem.2020.00737

Eguchi, Keiichi. 1988. The Sino-Japanese Opium War. Iwanami Shoten, Tokyo. 209pp. ISBN: 9784004300298

Funayama, Shinji. 2013. The Science of Poison: The Relationship Between Poison and Humans - A Cultural and Historical Approach to How Poisons Have Been Used and Understood. Natsume Publishing, Tokyo. 239pp. ISBN: 9784816354090

Jesus, A., Bonhomme, V., Evin, A., Soteras, R., Jacomet, S., Bouby, L., & Antolín, F. 2023. Morphometrics of waterlogged archaeological seeds give new insights into the domestication and spread of Papaver somniferum L. in Western Europe. PloS One 18(5): e0286190. https://doi.org/10.1371/journal.pone.0286190

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

Ministry of Health, Labour and Welfare. 2019. How to distinguish between cannabis and opium poppies. Ministry of Health, Labour and Welfare, Tokyo. 14pp. https://www.city.minamata.lg.jp/kankyo/kiji003816/3_816_up_z8606xnm.pdf

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

Kumano, Naoki. 2019. Current Status and Challenges of Research on the History of Opium Policy in Modern Japan. Hosei Kenkyu (Legal and Political Studies) 85(3/4): 121-158. https://doi.org/10.15017/2230995

Narita, M., Fukuda, M., Hirai, K., & Ujihara, T. 1998. The history of opium poppy cultivation and opium: A study on its origin and spread. Shinshu University Faculty of Agriculture Bulletin 35(1): 59-64. http://hdl.handle.net/10091/868

Prentis, S. 2022. Speech! How language made us human. hogsaloft, 333pp. ISBN: 9781916893511

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

Samorini, G. 2019. The oldest archeological data evidencing the relationship of Homo sapiens with psychoactive plants: A worldwide overview. Journal of Psychedelic Studies 3(2): 63-80. https://doi.org/10.1556/2054.2019.008

Shimizu, K., Morita, H., & Hirota, S. 2001. Illustrated Guide to Naturalized Plants of Japan: 600 Species of Plant Invaders (Revised). National Rural Education Association, Tokyo. 553pp. ISBN: 9784881370858

Tokyo Metropolitan Institute of Public Health. 2008. How to Identify Illegible Poppies. Tokyo Metropolitan Medicinal Plant Garden. Pharmaceutical Research Department page. Tokyo Metropolitan Institute of Public Health website. https://www.tmiph.metro.tokyo.lg.jp/lb_iyaku/plant/tokyo-keshi

Yoshikawa, Masato. 2010. Papaver dubium L. (Long-headed poppy). Journal of the Japanese Society of Landscape Architecture 35(4): 556. http://www.jsrt.jp/pdf/dokomade/35-4nagamihinageshi.pdf

Wu, X., Raven, PH, & Hong, D. (Eds.). 2008. Flora of China (Vol. 7 Menispermaceae through Capparaceae). Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis. xii, 499pp. ISBN: 9781930723818

Corydalis ambigua, Corydalis fumariifolia, and Corydalis ambigua all belong to the Corydalis genus of the poppy family. What's interesting about them is that in the spring (April to June) when they bloom in the forest, their purple to bluish-purple flowers bloom in a spiral pattern facing in all directions. However, their flower shapes and habitats are similar, so they can sometimes be confused. These three species have various differences, but you can accurately distinguish them by first checking the shape of their leaves. If you forget to check the leaves, it's a good idea to check the color of the flowers, the shape of the bracts below the flowers, and the shape of the fruits. This article will explain the classification and morphology of the Corydalis genus.

What are Corydalis ambigua, Corydalis fumariifolia, and Corydalis ambigua?

Corydalis incisa, also known as purple corydalis, is a perennial herb distributed in Hokkaido, Honshu, Shikoku, Kyushu, and the Ryukyu Islands in Japan, as well as in China, growing in forests, on the edges of fields, and along roadsides (Kanagawa Prefecture Flora Survey Association, 2018).

Corydalis decumbens, also known as Jirobo Engosaku, is a perennial herb distributed in Honshu (west of the Kanto and Chubu regions), Shikoku, and Kyushu in Japan; as well as in China and Taiwan, growing in grasslands, forest edges, and between stone walls.

Corydalis lineariloba var. lineariloba, also known as mountain sedge, is a perennial herb distributed in Honshu and Kyushu in Japan, as well as in Korea, China, Amur, and Ussuri, growing in mixed forests and forest edges.

Both belong to the genus Corydalis in the poppy family, and what's interesting is that when they bloom in the spring (April to June) in the forest, their purple to bluish-purple flowers bloom in a spiral pattern facing in all directions. The Japanese name Murasaki-keman is said to come from the fact that the flowers face diagonally upwards or downwards, resembling the Buddhist ornament Keman (a decorative ornament hung in transoms, etc., in temples). However, the flowers of the Corydalis genus themselves do not resemble Keman very much, so it might be better to think that the name is derived from Lamprocapnos spectabilis, a close relative in the same poppy family. In this case, the flowers actually hang down.

The flower has four petals, but the two outer petals and the two inner petals have different shapes. The upper of the outer petals has a unique structure in which the back is pouch-shaped and protrudes, which gives it a very different appearance from other poppy flowers (Hayashi et al., 2013). The two inner petals are fused at the tips. This flower structure is the same in all three species and they are quite similar.

[Seed Plant Encyclopedia #119] What are the species of the poppy family? Photo list

The Papaveraceae family consists of herbaceous plants whose stems and leaves are often covered in a powdery white substance. Breaking the stem releases a milky white or orange-yellow sap. The leaves are alternate, pinnately lobed or pinnately compound, sometimes simple, and lack stipules. The flowers are bisexual, radially symmetrical, or bilaterally symmetrical. The sepals are 2-4 in number and separate...

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They also share the characteristic of having leaves that are twice-ternately compound.

They have similar habitats and can sometimes coexist.

Therefore, some people may not be able to tell the difference.

What are the differences between Corydalis ambigua, Corydalis fumariifolia, and Corydalis ambigua?

Several methods have been proposed to distinguish these three species, but I think it's best to identify them by their leaves (Kanagawa Prefecture Flora Survey Association, 2018).

All three species have compound leaves, but the difference is that Corydalis ambigua has serrated edges on its leaves, while Corydalis fumariifolia and Corydalis hyemalis do not.

Regarding Corydalis ambigua and Corydalis fumariifolia, the difference is that Corydalis ambigua has leaflets that are deeply divided into 2-3 lobes, while Corydalis fumariifolia has leaflets that are not divided and are linear to broadly ovate.

For the record, Corydalis incisa does not have tubers, while Corydalis ambigua and Corydalis fumariifolia do have tubers.

This results in a difference between Corydalis ambigua, which keeps its leaves up all year except in winter, and Corydalis fumariifolia and Corydalis radiata, which have their above-ground parts die back in summer and spend a long time underground until the following spring using their tubers as nutrients, becoming "spring plants."

This is a significant ecological difference, but it won't be helpful when trying to distinguish them in the wild during spring.

In addition, the flower colors are usually purple for Corydalis ambigua, pale reddish-purple for Corydalis fumariifolia, and pale purple for Corydalis ambigua, but there are many exceptions as will be discussed later.

The fruits are narrowly oblong in Corydalis ambigua, linear in Corydalis fumariifolia, and broadly lanceolate or ovate-oblong in Corydalis radiata.

While there are bracts at the base of the flower, in Corydalis ambigua and Corydalis fumariifolia, the bracts are tooth-shaped, whereas in Corydalis fumariifolia, the bracts are entire.

Are there any other similar species? Are there any varieties or cultivars?

Among the Corydalis ambigua species, there are varieties such as Corydalis fumariifolia f. pallescens, which has slightly smaller flowers with reddish-purple tips on the petals and is nearly white overall, and Corydalis fumariifolia f. candida, which has entirely white petals.

Among the Corydalis ambigua species, there is a known variety called Corydalis ambigua f. albescens, in which all of the petals are white.

Corydalis ambigua is known to have a variety called Corydalis fumariifolia var. capillaris, which is smaller overall and has fewer flowers (2-4) than Corydalis ambigua.

References

Hayashi, Yasaka, Kadota, Yuichi, and Hirano, Takahisa. 2013. Yamakei Handy Illustrated Guide 1: Wildflowers (Revised and Expanded New Edition). Yama-kei Publishers, Tokyo. 664pp. ISBN: 9784635070195

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

The Papaveraceae family consists of herbaceous plants whose stems and leaves are often covered in a powdery white substance, and which release a milky white or orange-yellow sap when the stem is broken. The leaves are alternate, pinnately lobed or pinnately compound, sometimes simple, and lack stipules. The flowers are bisexual, radially symmetrical, or bilaterally symmetrical. The sepals are 2-4 in number, free, deciduous, or persistent. The petals are usually 4 in number. The ovary is superior and has 1-8 lobes. The placenta is paramembrane. The fruit is either an indehiscent nut or a capsule that splits into lobes or has holes (perforated capsule) to scatter the seeds. Approximately 40 genera and 800 species are known, found in the tropical to subarctic regions of the Northern Hemisphere.

This article provides a comprehensive, field guide-style introduction to plants belonging to the poppy family.

The basic information is based on the Kanagawa Prefecture Flora Survey Association (2018). Photos are replaced as better ones become available. While the identification is done by the author, please note that misidentifications may be corrected without notice.

No.1128.a White Thistle Papaver (Argemone hispida)

Perennial (Flora of North America). Stems are 30-60 cm tall, densely covered with spiny projections, and have a crisp texture. Leaf blades: The upper surface has sparse or dense spiny projections between the veins; the abaxial surface (lower side of the leaf) has dense spiny projections on most of the midrib and main vein, while the adaxial surface (upper side of the leaf) has fewer spiny projections. Flowering occurs from spring to summer. The calyx is oblong, 16-20 x 14-18 mm, spiny and hair-like. The corners of the sepals are 4-7 mm, spiny, and the spines at the tips are flat and hard. Flowers are 7-10 cm wide, with white petals, more than 150 stamens, pale yellow filaments, and 3-4 pistils arranged in a spike. Fruiting occurs from summer to autumn. The capsule is oval, 30-40 x 12-18 mm (including stalk, excluding projections), with dense projections, an indistinct surface, and the longest projections erect or curved, about 5 mm long. The seeds are about 2.5 mm. It is native to the Laramie and Rocky Mountains of North America, inhabiting grasslands, slopes, and eastern hilly areas at elevations of 1400-2100 m. In Japan, it is rarely cultivated as an ornamental plant.

No.1132.a Siberian poppy (Papaver nudicaule)

This is a perennial herb, although it is not heat-tolerant and is treated as an annual in Japan when sown in autumn (Flora of China). It grows to a height of 20-60 cm and is highly variable. The taproot is cylindrical, growing well, with the upper part being 2-5 mm in diameter, acuminate or fusiform. The rhizome is short, thick, and usually unbranched. The stem is very short or seemingly absent. The leaves are clustered, all basal, with petioles (1-)5-12 cm long, spreading at the base to form a sheath, and covered with oblique bristles. The leaf blade is slightly powdery white on both sides, ovate to lanceolate, 3-8 cm long, densely to sparsely covered with gray bristles on both sides, rarely nearly glabrous, pinnately lobed to deeply pinnately lobed to completely pinnate, with 2-4 pairs of lobes, entire or again pinnately lobed to deeply pinnately lobed. The pinnae are narrowly ovate to narrowly lanceolate to oblong, with an acute to obtuse to rounded apex. Flowering occurs from May to September. The flower stalks are one to several, erect, cylindrical, and densely or sparsely covered with inclined, compressed bristles. The flowers are solitary, terminal, and borne on the flower stalk, cup-shaped, 4-6 cm in diameter. The buds are usually nutant, broadly ovate to spherical, 1.5-2 cm in diameter, and densely covered with brownish bristles. The sepals are two in number, deciduous, and corymbiform-elliptic. The petals are four in number, yellowish, yellow, orange, rarely red, broadly cuneate or obovate, (1.5-)2-3 cm long, with a short claw at the base and wavy-crenate margins. There are numerous stamens. The filaments are yellow or olive-colored, conical, 6-10 mm long. The anthers are yellowish-white to yellow, rarely reddish, oblong, 1-2 mm long. The ovary is obovate to narrowly obovate, 5–10 mm long, and densely covered with appressed bristles. The stigma has 4–8 lobes and is radially symmetrical. The capsule is narrowly obovate to obovate to obovate-oblong, 1–1.7 cm long, densely covered with appressed whitish-brown to reddish-brown bristles, and has 4–8 slightly broad ribs. The stigma disk is flat and has distinct notched crenate teeth. The seeds are numerous, brown, nearly kidney-shaped, small, striationd, and have honeycomb-like depressions. It is distributed in Afghanistan, Kazakhstan, Kyrgyzstan, China, Korea, Mongolia, Russia (including Siberia), Tajikistan, and Uzbekistan, and grows on forest edges, grasslands, meadows, slopes, pastures, valleys, river gravel, moraines, and roadsides. This species is highly variable, with varieties having yellow or orange petals and ovaries and capsules covered in bristles (f. nudicaule, same distribution as this species), varieties with the same characteristics but white petals (f. seticarpum, recorded from Heilongjiang, Jilin, and Inner Mongolia), varieties with yellow or orange petals and glabrous ovaries and capsules (var. aquilegioides, recorded from Gansu, Hebei, Heilongjiang, West Hubei, Inner Mongolia Autonomous Region, Ningxia Hui Autonomous Region, Shaanxi, Shanxi, and Eastern Sichuan), and varieties with the same characteristics but white petals (f. amurense, recorded from Heilongjiang, Jilin, and Inner Mongolia). However, cultivated plants known as "Icelandic poppies," which are grown as ornamental plants, are considered to have a complex origin, including several other closely related species, such as Papaver radicatum. They are also cultivated for ornamental purposes in Japan.

No.1132.b Papaver dubium subsp. dubium

This is an annual plant. It resembles the common poppy, but its Japanese name comes from the fact that its fruit is more elongated. The leaves are 1-2 times pinnately lobed. The flowers bloom from April to June, are 3-6 cm in diameter, orange-red, and have a radially arranged stigma. The fruit is oblong, 1.5-2.5 cm long. It is a naturalized plant native to Europe. In Japan, the first record was in Tokyo in 1961 (Yoshikawa, 2010). Seeds have been detected in imported grains, suggesting that it was an unintentional introduction, but its distribution has rapidly expanded since the 1990s, and it is now found in a wide area from Hokkaido to Kyushu. The "Illustrated Guide to Naturalized Plants" states that "it has recently been found sporadically in urban areas of Kitakyushu... (omitted)... there have also been reports of naturalization from Gunma Prefecture and Tokyo, but it is still rare nationwide." In recent years, it has increased remarkably in suburban areas and can be commonly seen along roadsides, in vacant lots, and around houses. In subsp. dubium, the petals overlap without gaps, and the sap is milky white (Yoshikawa, 2010).

No.1132.c Papaver dubium subsp. lecoqii

Lecoqii is a pseudonym used by the author. It is a subspecies of Papaver dubium (Yoshikawa, 2010) with gaps between its four petals and a yellow milky sap that oozes when the stem and leaves are cut. Both types have naturalized in Japan, but they are not distinguished in domestic field guides. Subsp. lecoqii blooms earlier, starting around the same time as Somei Yoshino cherry blossoms in the Tokyo area, while subsp. dubium is said to bloom about two weeks later. The following photos are of individuals that are thought to be the subspecies.

No.1133 Chelidonium majus subsp. asiaticum

This is a biennial herb, growing to a height of 30-80 cm. When the stem is broken, an orange-yellow sap is released, and leaves grow from the base, giving the entire plant a powdery white appearance. The leaves are 1-2 times pinnately lobed, and the leaflets are notched. Flowers bloom from May to July, in umbel-shaped inflorescences in the leaf axils. The flowers have four petals. The ovary has two placentas. It is distributed in Hokkaido, Honshu, Shikoku, Kyushu; Korea; Northeast China; and Sakhalin. It grows scattered in grasslands, forest edges, and between stone walls.

What are the differences between Greater Celandine and Japanese Kerria? We'll explain how to distinguish between similar species! Are they poisonous? Why do Greater Celandine flowers bloom at an angle?

Both *Chelidonium majus* and *Kerria japonica* are wild species of the poppy family, each with four yellow petals, so it can be difficult to distinguish between them. Their leaves can be identified by the presence or absence of serrations on the leaflets, and their flowers are almost identical, but there are differences in the arrangement of the inflorescence and the shape of the stamens and pistils…

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No. 1138 Macleaya cordata

Also known as Champagium. A perennial herb. It grows in sunny, barren areas. The stem is hollow and white, and when broken, it releases a dark orange sap. The underside of the leaves is densely covered with fine white hairs. The flowers bloom from June to August and are white. The anthers are linear and yellow. The fruit is broadly lanceolate, flattened and hairless, containing a few seeds. It is distributed in Honshu, Shikoku, Kyushu, China, and Taiwan. It is commonly found in urban areas, mountain roadsides, landslides, grasslands, and forest edges. A form with hairless undersides of the leaves is called Champagium f. glabra and grows mixed with the basic species.

What species are similar to Macleaya cordata? Is it toxic? What types of alkaloids does it contain? Is it medicinal? Did the flower's "petals" have been genetically altered to resemble "stamens"?

Macleaya cordata is a perennial herb that grows in wastelands and roadsides, and can occasionally be seen in urban areas. It belongs to the poppy family, and while no similar plants have been identified in Japan, several varieties are known, differing slightly in leaf morphology. The toxicity of Macleaya cordata is its most well-known characteristic; cutting the stem…

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No. 1140 Dicentra peregrina

This is a perennial plant. Its Japanese name comes from the fact that the shape of its flower resembles the face of a horse (or horse). It is called the "Queen of Alpine Plants" because of its beautiful flowers and its ability to grow in harsh environments where sand and gravel are constantly shifting and other plants cannot survive. It grows to a height of about 5 cm. The leaves are basal leaves, finely lobed and resembling parsley, and are covered with a white powdery coating. It flowers from July to August. The flower stalk is 10 to 15 cm long and bears pale pink flowers. There are four petals, two on the outside and two on the inside. The outer petals are greatly swollen at the base and curl back at the tip, while the inner petals are slightly smaller, constricted in the middle, and fused at the top. The stamens and pistil are contained within this tube. There are two sepals, which fall off quickly. Because it grows in sandy and gravelly areas where other plants cannot survive, it develops long roots of 50 to 100 cm, which is unimaginable from its above-ground appearance. While other species like Viola mandshurica grow in similar locations and may sometimes coexist, Viola mandshurica often forms solitary colonies. After the flowers wither, they develop into slender, oval-shaped, glossy black seeds about 1.2 cm long. It is distributed in Northeast Asia, including the Kuril Islands, Sakhalin, the Kamchatka Peninsula, and eastern Siberia, as well as in the sandy and gravelly areas of wind-swept rocky slopes in the alpine zones of Japan, from Hokkaido to the central region. Bumblebees inhabit the alpine zones, maintaining a body temperature of around 37°C as they fly around collecting nectar. The bumblebees cling to the tube of the inner petals and forcefully push their heads into the gap between the inner petals and the nectar-containing outer petals, bending the tube and splitting it open. The stamens and pistils emerge from within and touch the bee's underside, resulting in pollination (Tanaka and Hirano, 2000). It is also susceptible to nectar theft by Bombus terrestris (Suga, 2001).

No. 1143 Corydalis incisa

This is a biennial herb. The leaves are twice-ternate compound leaves, with the leaflets pinnately lobed. The flowering stalks are 20-50 cm tall. The flowers bloom from April to June and are reddish-purple. The fruit is linear-oblong and hangs downwards when ripe. It is distributed in Hokkaido, Honshu, Shikoku, Kyushu, the Ryukyu Islands, and China. It grows in forests, on the edges of fields, and along roadsides.

What are the differences between Corydalis ambigua, Corydalis fumariifolia, and Corydalis ambigua? An explanation of how to distinguish between similar species.

Corydalis ambigua, Corydalis fumariifolia, and Corydalis hyemalis all belong to the Corydalis genus of the poppy family. What's interesting about them is that in the spring (April-June) flowering season in forests, their purple to bluish-purple flowers bloom in a spiral pattern facing in all directions. However, their flower shapes and habitats are similar, so they can sometimes be confused…

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No.1143.1 Corydalis incisa

A variety with relatively small flowers, where only the tips of the corolla lobes are tinged with reddish-purple, and the entire flower is nearly white, is called Corydalis ambigua f. pallescens.

No. 1144 Corydalis decumbens

This is a perennial herb. The leaves are 2-3 times trifoliate compound leaves, with the leaflets deeply divided into 2-3 lobes. The flowering stalks are 5-10 cm tall. The flowers bloom in April-May and are pale reddish-purple. The fruit is linear, slightly constricted like a string of beads. It is distributed in Honshu (west of the Kanto and Chubu regions), Shikoku, Kyushu, China, and Taiwan. It grows in grasslands, forest edges, and between stone walls. Along with Corydalis ambigua, it is a "spring plant" whose above-ground parts wither in the summer and spend a long time underground until the following spring. A white-flowered variety is called Corydalis ambigua f. albescens.

What are the differences between Corydalis ambigua, Corydalis fumariifolia, and Corydalis ambigua? An explanation of how to distinguish between similar species.

Corydalis ambigua, Corydalis fumariifolia, and Corydalis hyemalis all belong to the Corydalis genus of the poppy family. What's interesting about them is that in the spring (April-June) flowering season in forests, their purple to bluish-purple flowers bloom in a spiral pattern facing in all directions. However, their flower shapes and habitats are similar, so they can sometimes be confused…

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References

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

Suga, Takeshi. 2001. Records of bumblebee visits to flowers and nectar robbing of *Dicentra peregrina* by *Bombus terrestris* in the alpine zone of the central Japanese Alps. Bulletin of the Nagano Prefectural Institute for Nature Conservation 4: 13-22. https://agriknowledge.affrc.go.jp/RN/2030702021

Tanaka, Hajime & Hirano, Takahisa. 2000. The Face of Flowers: Wisdom for Bearing Fruit. Yama-kei Publishers, Tokyo. 191pp. ISBN: 9784635063043

Yoshikawa, Masato. 2010. Papaver dubium L. (Long-headed poppy). Journal of the Japanese Society of Landscape Architecture 35(4): 556. http://www.jsrt.jp/pdf/dokomade/35-4nagamihinageshi.pdf

Both Greater Celandine and Japanese Kerria are wild species of the poppy family, composed of four yellow petals, so it can be difficult to distinguish between them. The leaves can be distinguished by the presence or absence of serrations on the leaflets, and the flowers are almost identical, but there are differences in the arrangement of the inflorescence and the shape of the stamens and pistils. Both species are poisonous, as they belong to the poppy family. Contact with the milky sap can cause inflammation, and ingestion of Greater Celandine is said to cause coma, respiratory paralysis, and peripheral nerve paralysis. Currently, it is not known medically how much exposure is safe for humans, but even small amounts can cause inflammation, so it is dangerous to touch them, and ingestion should absolutely be avoided. However, from an ecological perspective, these two species reveal different aspects. Like all members of the poppy family, their flowers only produce pollen and no nectar, so the number of insects that visit them is quite limited. The yellow, flat flower structure attracts hoverflies, which prefer yellow and can eat pollen even with short mouthparts. However, there is a theory that the flowers are deliberately tilted diagonally rather than straight up to specifically appeal to a type of bee called the long-horned bee. The seeds have elaiosomes and are dispersed by ants. This article will explain the classification, toxicity, pollination ecology, and seed dispersal of Greater Celandine and Japanese Kerria.

A wild species of poppy consisting of four yellow petals.

Chelidonium majus (grass yellow) (broad sense) is a perennial herb distributed across the European continent, Asia, parts of Northwest Africa, and Japan from Hokkaido to Kyushu, inhabiting sunny roadsides, grasslands, and forest edges (Hayashi et al., 2013).

This species is divided into two subspecies: Chelidonium majus subsp. majus is distributed in Europe, Southwest Asia, and North Africa, while Chelidonium majus subsp. asiaticum (in the narrow sense) is distributed in Hokkaido, Honshu, Shikoku, Kyushu; Korea, Northeast China, and Sakhalin.

Hylomecon japonica, also known as Japanese mountain jasmine, is a perennial herb distributed in Honshu (south of Miyagi Prefecture), Shikoku, and Kyushu in Japan, growing in clusters in wooded areas in mountainous regions.

Both are wild species belonging to the poppy family, and since Yamabukisou was once included in the genus Chelidonium, it can be difficult to distinguish between them, especially since both have flowers composed of four petals and are yellow.

[Seed Plant Encyclopedia #119] What are the species of the poppy family? Photo list

The Papaveraceae family consists of herbaceous plants whose stems and leaves are often covered in a powdery white substance. Breaking the stem releases a milky white or orange-yellow sap. The leaves are alternate, pinnately lobed or pinnately compound, sometimes simple, and lack stipules. The flowers are bisexual, radially symmetrical, or bilaterally symmetrical. The sepals are 2-4 in number and separate...

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Greater celandine and Japanese kerria can be distinguished by the shape of their leaves.

While Greater Celandine and Japanese Kerria were once classified in the same genus, they are now in different genera and are quite different from each other.

First, both have odd-pinnately compound leaves, but in Greater Celandine, the petiole is not twice as long as the leaf blade, it is deeply lobed once or twice, and the leaflets are rounded with some notches, whereas in Japanese Kerria, the petiole is more than twice as long as the leaf blade, it is deeply lobed only once, the leaflets are broadly ovate or elliptical, the tip is pointed, and it has notches and fine serrations.

The flowers are quite similar, but in Greater Celandine, several flowers are borne in stalked umbels, the flowers are 2-2.5 cm in diameter, the stamens have long filaments, and the pistil is curved, while in Japanese Kerria, 2-3 flowers are borne in the leaf axils, the flowers are 4-5 cm in diameter, the stamens have short filaments, and the pistil is not curved.

The toxicity of Greater Celandine and Japanese Kerria

When the plant is damaged, it exudes a yellow to orange milky sap, which is its most distinctive characteristic. One theory suggests that the Japanese name for this species, "kusano-ki" (grass yellow), comes from this characteristic (Iwatsuki, 2006).

However, this type of milky sap is also produced by *Kerria japonica*, so it's not unique to *Chelidonium majus*. Such toxic milky sap is common in the poppy family, with the opium of * Papaver somniferum * being a prime example. The only difference is that this particular sap is yellow.

The milky sap can cause inflammation if it comes into contact with the skin, and in the case of Greater Celandine, accidental ingestion is known to cause coma, respiratory paralysis, and peripheral nerve paralysis (Satake, 2012). In the case of Japanese Kerria, accidental ingestion can cause nausea and respiratory paralysis.

However, perhaps because its toxicity has been widely known for a long time, the medical lethal dose remains unclear.

The plant contains many chelidonium alkaloids, and in the case of celandine, chelidonine, protopine, chelidimerine, sanguinarine, chelerythrine, malic acid, berberine, and chelidonic acid have been identified (Okada and Mitsuhashi, 1988).

Historically, it has been used as a medicine and herb. In traditional Chinese medicine, the dried above-ground parts harvested when they are still in bud are called "bai qu cai" and were used especially for treating skin diseases such as warts, athlete's foot, and jock itch, as well as wounds. When brewed and taken orally, it was believed to act as an anti-inflammatory and analgesic, and was thought to be effective against internal organ diseases such as stomach ailments. It was also used as a topical medicine for skin diseases such as eczema, scabies, ringworm, and warts. Because of this history, there is a theory that it is the "king of sores" because it is an effective medicinal herb for treating skin diseases.

However, its use has decreased over time due to its high toxicity. On the other hand, it has recently been scientifically re-evaluated, and its potential effectiveness in treating viral warts has been suggested (Nawrot et al., 2020).

It seems that drawing the line between medicine and poison is indeed difficult.

Poppies do not produce nectar; they only produce pollen.

Greater celandine (Chelidonium majus) blooms from April to July. It bears several flowers in stalked umbels. The flowers consist of four bright yellow petals and are about 2 cm in diameter, making them bright and conspicuous. Between the numerous stamens, a pistil can be seen that resembles a wriggling caterpillar (Hayashi et al., 2013).

Kerria japonica blooms from April to June. It bears one or two yellow flowers on pedicels 4-6 cm long in the upper leaf axils. The petals consist of four parts and are 2-2.5 cm long. There are many stamens. The style is short and the stigma is bifurcated.

Both flowers consist of four petals and are yellow. Common to all poppy family flowers is the structure where the entire pistil is aligned with the stamens. This type of flower structure is called "superior ovary," and it gives a slightly different impression from the yellow flowers of the rose family and daisy family (Kobayashi, 2007).

The most distinctive feature is the stamen, which has a very swollen tip. Why is it like this?

Poppy flowers, including this species, produce only pollen and no nectar (Tanaka, 2009). Therefore, it is thought that all the energy that would be used to produce nectar is instead directed towards pollination, resulting in this appearance.

Generally, pollen contains more protein than nectar, making it an important source of nutrients not only for the insect's body but also for female insects that need to lay eggs. This may be a way for them to differentiate themselves from other plants. The superior position of the ovary may also be due to factors such as increasing the chances of insects stepping on the pistil and transferring pollen while searching for it.

Why do they bloom at an angle?

What kinds of insects visit the flowers of the Greater Celandine plant?

Actual studies suggest that hoverflies are prevalent (Tanaka & Hirano, 2000). Hoverflies are known to prefer yellow flowers, have short proboscises, and favor flowers where the distance to nectar and pollen is short. Indeed, they are quite conspicuous and flat, making them easy to enter, so this possibility seems likely. However, don't you get the impression that these flowers are blooming at a considerable angle compared to other yellow flowers such as those in the Asteraceae family?

According to researchers who have studied this flower, a type of bee called the long-horned bee (Oenothera biennis) also visits it. Long-horned bees generally prefer flowers that bloom sideways, like the butterfly-shaped flowers of the legume family, and have complex structures. While the celandine flower (Chelidonium majus) doesn't bloom this way, researchers believe that its slightly sideways blooming might be an appeal to the long-horned bee.

Of course, there's a lack of research to confirm this, but perhaps even the slightest tilt in which a flower blooms is more important for survival than people realize.

There is insufficient research on the insects that visit the flowers of the Japanese kerria.

The fruit is a capsule, and the seeds are dispersed by ants.

Both fruits are capsules that split open when dry to release seeds (Hayashi et al., 2013), and the seeds have elaiosomes attached and are known to be dispersed by ants (Nakanishi, 1999; Kobayashi, 2007).

However, it seems that the specific species of ants that carry the seeds are not yet clear. The habitat range would likely vary considerably depending on the type of ant. We look forward to future research.

References

Hayashi, Yasaka, Kadota, Yuichi, and Hirano, Takahisa. 2013. Yamakei Handy Illustrated Guide 1: Wildflowers (Revised and Expanded New Edition). Yama-kei Publishers, Tokyo. 664pp. ISBN: 9784635070195

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

Iwatsuki, Hideaki. 2006. A book that clearly explains common weeds and wild plants found in urban areas. Shuwa System, Tokyo. 527pp. ISBN: 9784798014852

Nakanishi, Hiroki. 1999. Seed dispersal by ants. In: Ueda, Keisuke (Ed.), Seed Dispersal: The Evolution of Mutual Aid Vol. 2: Forests Created by Animals (pp. 104-117). Tsukiji Shokan. ISBN: 9784806711933

Nawrot, J., Wilk-Jędrusik, M., Nawrot, S., Nawrot, K., Wilk, B., Dawid-Pać, R., … & Gornowicz-Porowska, J. 2020. Milky sap of greater celandine (Chelidonium majus L.) and anti-viral properties. International Journal of Environmental Research and Public Health 17(5): 1540. ISSN: 1660-4601, https://doi.org/10.3390/ijerph17051540

Okada, Minoru & Mitsuhashi, Hiroshi. 1988. Makino's Illustrated Encyclopedia of Japanese and Chinese Medicinal Plants in Color. Hokuryukan, Tokyo. 782pp. ISBN: 9784832600041

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

Tanaka, Hajime. 2009. Handbook of Flowers Attracting Insects. Bun-ichi Sogo Shuppan, Tokyo. 80pp. ISBN: 9784829901397

Tanaka, Hajime & Hirano, Takahisa. 2000. The Face of Flowers: Wisdom for Bearing Fruit. Yama-kei Publishers, Tokyo. 191pp. ISBN: 9784635063043

Macleaya cordata is a perennial herb that grows in wastelands and roadsides, and can occasionally be seen in urban areas. It belongs to the poppy family, and although no similar plants have been identified in Japan, several varieties are known, with slight differences in leaf morphology. Macleaya cordata is most famous for its toxicity; when the stem is cut, it exudes a poisonous yellow sap. This sap can cause dermatitis and rashes if it comes into contact with the skin, so it should not be touched. Ingestion can cause vomiting, diarrhea, intoxication, low blood pressure, and respiratory paralysis. This toxicity affects not only humans but also Japanese deer and insects. The main components of the poison in Macleaya cordata are the alkaloids sanguinalin and quererythrin. On the other hand, in China, it has been used as a medicine for external application, and has a history of being used for dermatitis and skin infections, and its scientific application is being considered in Western medicine. The flower of Macleaya cordata is very unique. The flower lacks petals, and the sepals disappear after flowering, so it is essentially composed only of stamens and pistils. This is the result of a mutation called homeosis, which converts petals into stamens. This is thought to be a bold change necessary for wind pollination. However, strangely, there are records of bees visiting this inconspicuous flower. The reason is unknown, but it may also be supplemented by insect pollination. The fruit is a flattened capsule, which is also dispersed by wind, but the seeds have elaiosomes and are further dispersed by ants. This article will explain the classification, history, uses, toxicity, medicinal uses, pollination ecology, and seed dispersal of Macleaya cordata.

Perennial plants found in wastelands

Macleaya cordata, also known as Champa-giku, is a perennial herb distributed in Honshu to Kyushu in Japan, as well as in China and Taiwan, growing in sunny wastelands and roadsides (Wu et al., 2008; Hayashi et al., 2013). It belongs to the poppy family.

It grows to a height of 1-2 meters and is covered in a powdery white substance. The stem is hollow and, when cut, exudes a poisonous yellow milky sap. The leaves are 10-30 cm long, lobed like chrysanthemum leaves, and usually densely covered with curly hairs on the underside.

There are two theories about the origin of its Japanese name: one suggests it comes from "take-ni-gusa" (bamboo-like grass), referring to its hollow stems and winter-withered appearance resembling bamboo or dwarf bamboo; the other suggests it comes from "take-ni-gusa" (bamboo-boiled grass), suggesting that boiling it with bamboo softens the bamboo, making it easier to work with. However, it seems there is no actual evidence that it softens bamboo.

The alternative name "Champa-giku" (占城菊) comes from the fact that the leaves have notches and serrations around the edges, making them similar to the Asteraceae family. As for "Champa," there are two theories: one is that it means a chrysanthemum that came from a southern country like Champa in southern Vietnam, and the other is that it comes from the rattling sound the fruit makes when it sways in the wind. However, there is no evidence that Macleaya cordata is distributed in Vietnam. Furthermore, Macleaya cordata is a native species.

Are there any species that resemble Macleaya cordata?

Macleaya microcarpa belongs to the poppy family, but a similar plant found in China is called Macleaya microcarpa, which has fewer stamens (8-12) (Wu et al., 2008). However, it is not found in Japan. Therefore, you would rarely have trouble distinguishing between Macleaya microcarpa and other similar plants.

However, several varieties of Macleaya cordata have been identified.

Macleaya cordata f. glabra is a variety that has almost no hairs on the petioles or underside of the leaves.

Additionally, Macleaya cordata f. koaraii is a variety with circular leaves that have deep incisions.

[Seed Plant Encyclopedia #119] What are the species of the poppy family? Photo list

The Papaveraceae family consists of herbaceous plants whose stems and leaves are often covered in a powdery white substance. Breaking the stem releases a milky white or orange-yellow sap. The leaves are alternate, pinnately lobed or pinnately compound, sometimes simple, and lack stipules. The flowers are bisexual, radially symmetrical, or bilaterally symmetrical. The sepals are 2-4 in number and separate...

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How toxic is Macleaya cordata? What types of alkaloids does it contain?

Macleaya cordata is poisonous; when its stem is cut, it releases a toxic yellow milky sap. This sap is found not only in the stem but also in the leaves, petioles, and above-ground stems—the entire plant. This is similar to that of other poppy family members such as Greater Celandine and Kerria japonica. Such toxic milky saps are common in the poppy family, the most representative being the opium of the poppy Papaver somniferum.

What are the differences between Greater Celandine and Japanese Kerria? We'll explain how to distinguish between similar species! Are they poisonous? Why do Greater Celandine flowers bloom at an angle?

Both *Chelidonium majus* and *Cornus kousa* are wild species of the poppy family, composed of four yellow petals, so it can be difficult to distinguish between them. Their leaves can be differentiated by the presence or absence of serrations on the leaflets, and their flowers are almost identical, but there are differences in the arrangement of the inflorescence and the shape of the stamens and pistils...

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If the lotion gets on your hands, it can cause dermatitis and a rash, so you should not touch it (Satake, 2012).

What happens if it is ingested orally?

The lethal dose for humans is unknown, but ingestion can cause vomiting, diarrhea, intoxication, low blood pressure, and respiratory paralysis (Satake, 2012).

Experiments have been conducted in rats, and the median lethal dose (_LD50) for oral ingestion of an aqueous solution of Macleaya cordata was 900 mg/kg, while the median lethal dose for oral ingestion of sanguinalin chloride, which contains Macleaya cordata, was 1,658 mg/kg (Lin et al., 2018).

Such toxicity to mammals is also utilized in nature; it has been found that the Japanese deer (Cervus nippon) does not eat this plant at all (Uchimura, 2014).

Furthermore, it is said that in the past, the liquid extracted by boiling Macleaya cordata was used as an insecticide spray (Iwatsuki, 2006). Therefore, it is thought that it also has an insecticidal effect against leaf-eating insects.

The toxic components of Macleaya cordata are very diverse, but they have been shown to be mainly isoquinoline alkaloids, and in particular, the benzophenanthryzine alkaloids sanguinarine and chelerythrine are considered to be characteristic components of the Macleaya cordata genus (Lin et al., 2018).

Was Macleaya cordata also used as medicine?

On the other hand, in China, Macleaya cordata has been used externally as a medicine, mainly to treat inflammation and certain skin diseases (Lin et al., 2018).

The main components responsible for its effects are also sanguinalin and querellithrin.

Macleaya cordata was first listed in the "Bencao Shiyi," a traditional Chinese medicine text written by Chen Zangqi in 739 during the Tang Dynasty. It was prescribed only for external use, and its toxicity was also described.

Traditionally, it was used as a common remedy to temporarily relieve muscle pain, treat bee stings, and heal inflamed wounds. In folk medicine, the leaves were also commonly used to treat bruises, ulcers, rheumatism, scabies, and other skin conditions.

In traditional Chinese medicine, it is still widely used today to treat wounds, trichomoniasis, arthritis, and rheumatic joint pain. Extracts of Macleaya cordata are also used topically to treat skin conditions.

Clinical studies in China have shown that bathing with Macleaya cordata cures scabies, genital itching, and tinea corporis. Macleaya cordata roots are also administered as an alternative therapy to cancer patients. Furthermore, in livestock, Macleaya cordata injections are believed to be effective against swine dysentery, white diarrhea, edema, paratyphoid fever, and porcine infectious gastroenteritis due to their detoxifying, antibacterial, and anti-inflammatory properties. In addition, it is sometimes used as a skin cleanser, antipruritic, and treatment for centipede bites.

In North America and Europe, it is sometimes used as a traditional medicinal plant to treat insect bites and ringworm infections.

This truly demonstrates that it can be both poison and medicine. Western medicine often uses antibiotics, but problems associated with their overuse (such as drug residues and the emergence of antibiotic-resistant bacteria) are also known. The natural active ingredients contained in Macleaya cordata have the same effects as conventional antibiotics, but are easily metabolized into non-toxic metabolites, have no residue, and are thought to be less likely to cause drug resistance due to their complex active ingredients and unique mechanism of action. Applied research is currently underway on this topic.

What is the structure of a Macleaya cordata flower? Which part is the flower?

Macleaya cordata flowers in July and August, blooming in the summer and forming large conical inflorescences at the tips of its stems. When in bud, it is enclosed by two white sepals and looks no different from an ordinary flower, but once it opens, these sepals disappear, making it difficult to tell at first glance which is the flower.

However, within the buds, there are organs that spread out in a linear fashion. Upon closer inspection, a pistil is visible in the center, and 24 to 30 of these radiating structures clearly have anthers and are stamens. This is the actual flower. This flower has no petals, and the sepals fall off as soon as it opens, meaning it is essentially composed only of stamens and pistils. Plants with flowers of this structure are quite rare.

Why did the flowers of Macleaya cordata develop this structure?

How does this flower lose its petals and create a flower consisting only of stamens? I find the radial arrangement of the stamens particularly strange.

It has been discovered that this actually utilizes a gene mutation called "homeosis." Homeosis refers to a change in which, due to genetic causes (a mutation in a certain gene, or an abnormality in its expression), some organs do not take on their original form but instead transform into other homologous organs.

It may be a little difficult to understand, but in the case of Macleaya cordata, the genetic mechanism that would normally produce petals is converted to produce stamens (Ronse De Craene & Smet, 1993; Ronse De Craene, 2003)! This can be said to be a very unique change.

But why are these changes happening?

While this hasn't been fully observed through experimental studies, researchers familiar with plant morphology in the UK believe it's primarily an adaptation for wind-borne pollen dispersal (Ronse De Craene, 2003).

By eliminating the petals that attract insects, the flower reduces wasted energy and also allows air to pass through more easily. The increased number of stamens also increases pollen production, which is then carried by the wind, significantly increasing the chances of the pollen landing on the pistil of another flower.

In fact, in Japan, pollen from Macleaya cordata has been detected as airborne pollen, just like that from Japanese cedar and ragweed (Sahashi, 1987). Therefore, it seems certain that the pollen is being dispersed by the wind.

Considering this, it seems plausible that the formation of fairly large inflorescences, the long stamens, and the large pistils are all evolutionary adaptations specifically for wind-driven propagation (forestplant, 2019).

Macleaya cordata grows in barren areas, open spaces without obstacles like trees. Therefore, it relies on wind for pollination, which is likely more efficient than insect pollination.

It might not be purely wind-pollinated!?

However, the fact that nature doesn't always allow for easy understanding is both its difficulty and its fascination.

Surprisingly, it has been observed that bees, including bumblebees, visit the flowers of Macleaya cordata (Tanaka, 1976; Ichikawa et al., 2011).

Logically, the flowers of Macleaya cordata lack any petal-like organs that would attract insects, and therefore should not appear attractive to them at all. However, two studies have actually confirmed that bees do visit them.

It's unclear whether this is a waste of energy for Macleaya cordata, as only its pollen is being eaten, or whether it actually has a pollinating effect, or if it's simply an extremely rare occurrence. However, recent research is revealing that flowers of plants that appear to have only one method of pollination actually have multiple methods. For example, the castor bean plant (Ricinus communis) was once thought to be a flower solely reliant on wind pollination, but it is now known that pollination is also promoted by honeybees. Furthermore, even insect-pollinated flowers, which are thought to have evolved as specialists, frequently rely on insects from different taxonomic groups for pollination during the day and night.

How toxic is castor bean? What are its components? What are the uses of castor oil? Why is it considered safe despite being toxic? Its flowers are pollinated by both wind and insects! Its seeds are dispersed automatically and by ants!

Castor bean is a perennial plant said to originate from northeastern Africa, cultivated worldwide for commercial and ornamental purposes, and sometimes naturalized. It's almost impossible to mistake it for anything else. Its seeds, called "himashi," are rich in oil, and the extracted "castor oil" is used in cosmetics, shampoos, soaps, and more...

ecological-information.com

In the case of Macleaya cordata, it may also rely on bees for pollination as a supplementary measure. However, the mechanism behind this is still not well understood.

The fruit is a capsule, and the seeds are dispersed by a combination of wind and ants.

The fruit is a capsule, about 2.5 cm long and flattened into a sheath. The seeds are 1.5–2.2 mm long, with a bumpy, glossy brown surface and an elaiosome attached. The elaiosome is a small, yellowish-white tissue.

The capsules are clearly flattened, allowing the wind to carry the fruits, which are then dispersed to various locations. In areas where they grow in clusters, the wind causes the capsules to sway and the seeds to make a sound that resembles a human whisper, hence the name "whispering grass."

Up to this point, one might be able to predict this from the shape of the capsule. However, that's not all; as mentioned above, the seeds inside have elaiosomes attached. Elaiosomes are known to be food for ants, and the ants that seek them out disperse the seeds, further expanding their habitat (Kobayashi, 2007).

Similar to pollination, this aspect is also a good adaptation to life in open, windy, barren land.

There doesn't seem to be any comprehensive research on which specific ant species disperses the seeds, but Kobayashi (2007) photographed the black garden ant Messor aciculatus carrying the elaiosome from the pericarp of a seed. Black garden ants are known to collect seeds of grasses and other plants in the autumn. Since it's not a species found everywhere, it's unlikely that this ant species is the only one that disperses the seeds, but it certainly coincides well with the fruiting period of Macleaya cordata.

Looking at it this way, it seems that this plant is cleverly designed to make the most of the wind, both in its flowers and fruits, in order to survive in barren land.

References

forestplant. June 28, 2019. Macleaya cordata flowers. Natural history of forests, trees, flowers, and fruits. http://forestplant.blog.fc2.com/blog-entry-42.html

Hayashi, Yasaka, Kadota, Yuichi, and Hirano, Takahisa. 2013. Yamakei Handy Illustrated Guide 1: Wildflowers (Revised and Expanded New Edition). Yama-kei Publishers, Tokyo. 664pp. ISBN: 9784635070195

Ichikawa, S., Kurahashi, T., & Ikuru, S. 2011. Possibility of a novel pollination mode by flower-visiting bees and yellow-breasted bumblebees collected in Kagawa Prefecture. Bulletin of the Faculty of Agriculture, Kagawa University 63(116): 43-59. ISSN: 0368-5128, http://id.nii.ac.jp/1731/00003553/

Iwatsuki, Hideaki. 2006. A book that clearly explains common weeds and wild plants found in urban areas. Shuwa System, Tokyo. 527pp. ISBN: 9784798014852

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

Lin, L., Liu, YC, Huang, JL, Liu, XB, Qing, ZX, Zeng, JG, & Liu, ZY 2018. Medicinal plants of the genus Macleaya (Macleaya cordata, Macleaya microcarpa): A review of their phytochemistry, pharmacology, and toxicology. Phytotherapy Research 32(1): 19-48. https://doi.org/10.1002/ptr.5952

Ronse De Craene, LP 2003. The evolutionary significance of homeosis in flowers: a morphological perspective. International Journal of Plant Sciences 164(S5): S225-S235. ISSN: 1058-5893, https://doi.org/10.1086/376878

Ronse De Craene, LP, & Smets, E. 1990. The systematic relationship between Begoniaceae and Papaveraceae: a comparative study of their floral development. Bulletin du Jardin Botanique National de Belgique 60(3/4): 229-273. ISSN: 0303-9153, https://doi.org/10.2307/3668215

Tanaka, Hajime. 1976. Observation of insect-pollinated and wind-pollinated flowers. New Science Co., Ltd., Tokyo. 109pp. ISBN: 9784821600236

Sahashi, Norio. 1987. Airborne pollen as biological particulate matter and hay fever. Journal of the Japan Society of Powder Technology 24(3): 154-161. ISSN: 1883-7239, https://doi.org/10.4164/sptj.24.154

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

Uchimura, Yoshihiko. 2014. How far can we take greening plants? Macleaya cordata (Willd.) R.Br. 40(2): 390. ISSN: 0916-7439, http://www.jsrt.jp/pdf/dokomade/40-2_takenigusa.pdf

Wu, X., Raven, PH, Hong, D. (Eds.). 2008. Flora of China (Vol. 7 Menispermaceae through Capparaceae). Science Press, Beijing, and Missouri Botanical Garden Press, St. Louis. xii, 499pp. ISBN: 9781930723818

Source

This article is a significantly expanded version of a piece originally published in the following book.