Euonymus japonicus, Euonymus fortunei, and Euonymus sieboldii all belong to the Euonymus genus of the Celastraceae family and are common trees in forests throughout Japan. Furthermore, they are frequently planted in urban areas for ornamental purposes and as hedges. These three species are broadly classified into Euonymus japonicus, Euonymus fortunei, and Euonymus sieboldii based on whether they are evergreen or deciduous, and Euonymus japonicus and Euonymus fortunei can be mainly distinguished by their growth patterns. Euonymus japonicus is sometimes confused with Aucuba japonica and Cleyera japonica, which are also evergreen trees, but their leaf and flower shapes are quite different upon closer observation. This article will explain the classification and morphology of the Euonymus genus.

What are Masaki, Tsurumasaki, and Mayumi?

Euonymus japonicus, also known as Japanese spindle tree (Masaki), is distributed in Hokkaido (southern part), Honshu, Shikoku, Kyushu, the Ryukyu Islands, and the Ogasawara Islands in Japan, as well as in China. It is an evergreen shrub that grows abundantly in coastal areas and is used for hedges (Kanagawa Prefecture Flora Survey Association, 2018).

Euonymus fortunei var. radicans, also known as Tsurumasaki, is an evergreen climbing woody plant that grows in hilly to mountainous areas and is distributed in Hokkaido, Honshu, Shikoku, Kyushu, and Amami in Japan; as well as in southern Korea and China.

Mayumi (Euonymus sieboldianus var. sieboldianus), also known as Kansai Mayumi, is a deciduous shrub or small tree that grows in hilly and mountainous areas and is distributed in Honshu, Shikoku, Kyushu, Tsushima, and Yakushima in Japan, as well as in Korea and China.

Both belong to the Euonymus genus of the Celastraceae family and are common trees in forests throughout Japan. Furthermore, they are frequently planted in urban areas for ornamental purposes or as hedges, to the point that it seems you can't go a day without seeing them.

However, since they belong to the same genus, they are very similar in that their leaves have fine serrations and their flowers are white and composed of four petals, so some people might confuse them.

What are the differences between Euonymus japonicus, Euonymus fortunei, and Euonymus sieboldianus?

These three species can be broadly divided into two groups (Kanagawa Prefecture Flora Survey Association, 2018; Hayashi, 2019).

While Euonymus japonicus and Euonymus fortunei belong to the " Ilicifolius " section within the Euonymus genus, Euonymus sieboldii belongs to the " Melanocarya " section.

Therefore, there are differences in their characteristics; specifically, Euonymus japonicus and Euonymus fortunei are evergreen trees, while Euonymus sieboldianus is a deciduous tree.

In other words, while Euonymus japonicus and Euonymus fortunei retain their leaves even in winter, Euonymus sieboldii loses its leaves in winter, leaving only branches.

You can determine whether a tree is evergreen or deciduous even outside of winter. Euonymus japonicus and Euonymus fortunei are evergreens and have glossy, thick leaves like most trees, while Euonymus sieboldii are deciduous and have thin, dull leaves like most trees.

These points can be used to broadly categorize them.

Furthermore, regarding the flowers, there is a difference in that the flower stalks of Euonymus japonicus and Euonymus fortunei are thick and short, while those of Euonymus sieboldii are thin and long.

While there are few reliable distinguishing features between Euonymus japonicus and Euonymus fortunei, the main difference is that Euonymus japonicus is an upright shrub, while Euonymus fortunei is a climbing woody plant.

Furthermore, while the size of the leaves in Euonymus japonicus is basically the same regardless of where they grow from, Euonymus fortunei has a difference in that it has much smaller leaves, about 2-3 cm in size, on branches that creep along the ground.

I think it's best to distinguish them based on these two points. I've also checked botanical guides that describe the differences between the leaves of Euonymus japonicus and Euonymus fortunei, but since there is considerable variation in the leaves of these two species, I don't think they are very helpful.

I haven't observed any clear differences regarding the flowers either.

What are the varieties of Euonymus japonicus, Euonymus fortunei, and Euonymus sieboldianus?

Euonymus japonicus, Euonymus fortunei, and Euonymus sieboldii all exhibit considerable variation, and a large number of varieties are known.

Besides the long-lasting bracts of Euonymus japonicus, Euonymus rugiosus, which has very uneven leaves, and the large-leaved Euonymus macrophyllus, there are also variegated varieties such as 'Albomarginatus' with white variegation, Euonymus aureovariegatus with yellow variegation, and Euonymus nakawaensis and Euonymus kiifukurinensis, which have yellow variegation inside the leaves. On the coast, there are also Euonymus kaiganensis var. littoralis, Euonymus sieboldiana var. obovatus, and Euonymus radicifer, but the detailed differences between them are not well known.

There are several varieties of Euonymus fortunei, including Euonymus fortunei f. angustifolius, Euonymus fortunei f. carrierei, and Euonymus fortunei f. rugosus, which has leaves with a pronounced uneven surface.

There are several varieties of Euonymus, including Euonymus yedoensis var. yedoensis, which has stronger and larger branches and leaves than the parent species; Euonymus megaphyllus var. megaphyllus, which is distributed in Hokkaido and Honshu (Hokuriku region and Sado Island); and Euonymus yumotoensis var. sanguineus, which has papillae on the veins on the underside of the leaves.

What are the differences between Masaki, Aoki, and Sakaki?

The differences between Euonymus japonicus, Aucuba japonica, and Cleyera japonica are also frequently searched for on the internet. Indeed, they are all evergreen trees that are commonly cultivated in urban areas.

However, Aucuba japonica belongs to the Aucubaceae family, while Cleyera japonica belongs to the Cleyera family, so their classifications are completely different.

The leaves of the Sakaki tree are entire and have no serrations, unlike the Masaki tree which has serrated leaves.

The leaves of Aucuba japonica are large and have coarse serrations, unlike those of Euonymus japonicus, which have small, fine serrations.

The other flowers and fruits are completely different. Please compare them with the photos in the other article for more details.

What are the differences between Aucuba japonica, Aucuba japonica var. serrata, and Aucuba japonica var. japonica? We explain how to distinguish between similar species! Only fungus gnats were visiting the inconspicuous flowers!? Only bulbuls were eating the fruit!?

Aucuba japonica is distributed in evergreen broad-leaved forests of East Asia and is a very common plant in Japan, even in urban areas, where it's rare to go a day without seeing it. Several varieties of Aucuba japonica are known, and they are often classified into Aucuba japonica (in the narrow sense), Aucuba japonica var. nangokuensis, and Aucuba japonica var. dwarf. The differences between them are not easily discernible from their names alone...

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What are the differences between Eurya japonica, Eurya japonica, and Sakaki? We'll explain how to distinguish between similar species! Do they bloom in early spring because they rely on bees and flies for pollination?

Hisakaki, Hamahisakaki, and Sakaki all belong to the family Cleyera (or Theaceae). Hisakaki and Sakaki, in particular, have been considered "yorishiro" (objects that house divine spirits) in Shintoism since ancient times and have been traditionally cultivated in Japan. However, their similar names may often lead to confusion...

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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

Eurya japonica, Eurya japonica var. japonica, and Sakaki cypress all belong to the family Podocarpaceae (also known as the Theaceae family). In particular, Eurya japonica and Sakaki cypress have been considered "yorishiro" (objects that house deities) in Shintoism since ancient times and have been traditionally cultivated in Japan. However, their names are similar, and they may often be confused. However, the differences between them are quite clear when compared. They can be broadly divided into two groups: Eurya japonica/Eurya japonica var. japonica and Sakaki cypress, with significant differences in leaf arrangement, leaf margins, and sexual systems. Eurya japonica and Eurya japonica var. japonica can be reliably distinguished by observing their habitats, as well as their leaf veins, leaf tips, and leaf margins. The flowers of Eurya japonica, which bloom in early spring, seem to rely on small, cold-hardy bees and flies for pollination. This article will explain the classification, morphology, and ecology of the genera Eurya japonica and Sakaki cypress.

What are Hisakaki, Hamahisakaki, and Sakaki?

Eurya japonica, also known as Hime-sakaki, is an evergreen small tree or shrub widely distributed throughout Japan (south of Iwate and Akita prefectures), Shikoku, Kyushu, the Ryukyu Islands, and the Ogasawara Islands, as well as southern Korea, except in the beech forest zone.

Eurya emarginata, also known as beach prawn sakaki, is an evergreen small tree that grows abundantly along the coast and is distributed in Honshu (west of Chiba Prefecture), Shikoku, Kyushu, and Okinawa in Japan; the Korean Peninsula; and China. It is also used in park plantings and as a street tree.

Sakaki (Cleyera japonica) is also known as Honsakaki or Masakaki. It is an evergreen small tree that grows in mountainous areas and is distributed in Honshu (southwest), Shikoku, Kyushu, and the Ryukyu Islands in Japan; as well as in Korea, China, and Taiwan.

Both belong to the family Cleyera (or Theaceae), and in particular, Hisakaki and Sakaki have been considered "yorishiro" (objects that house the spirits of the gods) in Shinto since ancient times. They are widely planted in shrines and are also offered at household altars, placed in ceramic flower vases called "sakaki-tate" (however, nowadays, Chinese specimens are often used (Dai & Fujishima, 2010)).

Morphologically, both are evergreen trees, their flowers have five sepals and five petals that are fused together at the base, and their fruits ripen to black.

Furthermore, their names are similar, so they are often confused. The fact that their leaves are not particularly distinctive, and their flowers and fruits are quite inconspicuous, also contributes to the difficulty in distinguishing them.

What are the differences between Eurya japonica, Eurya japonica, and Sakaki?

However, although all three species belong to the family Theaceae, there are considerable morphological differences between them, as Eurya japonica and Eurya japonica are in the genus Eurya japonica, while Sakaki is in the genus Sakaki (Kanagawa Prefecture Flora Survey Association, 2018).

First, there is a difference in that the leaves of Eurya japonica and Eurya japonica are arranged in two rows and have serrated edges, while the leaves of Sakaki are arranged spirally and have entire edges.

This is the easiest difference to spot, and it's often sufficient to distinguish between them.

Just to add, there's another difference: Eurya japonica and Eurya japonica have unisexual flowers and are dioecious (having separate male and female plants), while Sakaki has hermaphroditic flowers and is monoecious (having both male and female flowers on the same plant).

In other words, while a single flower of Eurya japonica and Eurya japonica has either stamens or pistils, Sakaki has both stamens and pistils.

This point also helps us understand that these differ at the genus level.

I think it's easiest to distinguish between Eurya japonica and Eurya japonica by the shape of their leaves.

In Eurya japonica, the leaf tips are pointed, the veins are inconspicuous, and the leaf margins are flat, whereas in Eurya japonica, the leaf tips are concave, the veins are concave and prominent, and the leaf margins are curved backward.

While it's worth noting that the young branches of Eurya japonica are hairless, sometimes with sparse hairs only at the top, and remain green for a long time, compared to Eurya japonica, whose young branches are densely hairy and quickly turn grayish-brown, this difference should only be considered as a general guideline.

As mentioned above, in the wild, Eurya japonica tends to grow in forests, while Eurya japonica tends to grow on coastlines.

How is Eurya japonica pollinated?

Eurya japonica is dioecious, with a flowering period from March to April (Mogi et al., 2000). It bears clusters of 1 to 3 bell-shaped to urn-shaped flowers in the leaf axils. The flowers are 2.5 to 5 mm in diameter, bloom facing downwards, and have a strong odor. Female flowers are smaller than male flowers. The petals are yellowish-white and number 5, slightly fused at the base. The sepals are dark purple and number 5. The pedicels are short, about 2 mm long.

Male flowers have 12 to 15 stamens, but female flowers have reduced stamens, and there is only one pistil, which is also reduced in male flowers. The style of the pistil is deeply three-lobed and curves backward.

The Eurya japonica is one of the first trees to bloom in spring and is quite noticeable as it often grows in forests and around shrines. It is clearly an insect-pollinated flower, but what kind of insects pollinate it?

One interesting point is that Eurya japonica is dioecious, meaning it has separate male and female plants. In dioecious plants, pollination during periods of low temperature is generally considered difficult because it limits the activity of flower-visiting insects. However, this is not the case with Eurya japonica, and many individuals can be seen.

A recent study on this point was conducted in Japan (Tatsuno et al., 2023).

These results indicate that flies (especially Empididae and Chironomidae) and bees (Hymenoptera) are the primary visitors to the flowers. Furthermore, Hymenoptera visitors were more active at high temperatures, while Diptera were observed even at low temperatures.

Even more interestingly, in areas with a higher concentration of dipteran visitors, the fruiting rate and seed count were higher.

Diptera (flies) are generally far inferior to Hymenoptera (bees and wasps) in terms of pollination, as they are more social (they raise their young). However, they compensate for this shortcoming by having a very large number of individuals visiting flowers.

In other words, the Eurya japonica tree cleverly utilizes two groups of insects to successfully pollinate even during periods when insects are scarce.

How do you disperse the seeds of Eurya japonica?

The fruit of the Eurya japonica is a berry, spherical in shape with a diameter of 4-5 mm, ripening to a dark purple color in October and November, and containing numerous seeds.

It is believed that the fruits of Eurya japonica are mostly eaten by birds, thus dispersing the seeds (Manabe et al., 1993; Imanishi, 2006). Specifically, these include brown-eared bulbuls, pale thrushes, starlings, and Japanese white-eyes.

While young Eurya japonica trees can be seen in various places in secondary forests, this is likely largely due to seed dispersal by birds.

References

Dai, Songjun & Fujishima, Koji. 2010. Export strategies and profitability of Sakaki-producing areas in China. Agricultural Market Research 19(1): 42-47. https://doi.org/10.18921/amsj.19.1_42

Imanishi, Ayumi. 2006. * Eurya japonica Thunb.*. Journal of the Japanese Society of Landscape Architecture 32(2): 374. http://www.jsrt.jp/pdf/dokomade/32-2hisakaki.pdf

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

Manabe, T., Yamamoto, S., and Chiba, K. 1993. Seed dispersal characteristics of Eurya japonica in secondary Quercus serrata forests. Journal of the Japanese Society of Landscape Architecture 18(3): 154-161. https://doi.org/10.7211/jjsrt.18.154

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

Tatsuno, M., Sueyoshi, M., & Osawa, N. 2023. Pollination ecology of the early-spring-blooming dioecious shrub Eurya japonica (Pentaphylacaceae). Botany 101(5): 164-175. https://doi.org/10.1139/cjb-2022-0083

Ternstroemia gymnanthera is an evergreen tree that grows in relatively dry areas near the coast and is quite popular as a garden tree. However, because its leaves are entire and have no serrations, it lacks distinctive features and is often confused with completely different species such as Pittosporum tobira, Rhaphiolepis indica, and Ilex crenata. However, in most cases, it can be distinguished by observing the color of the petiole and the condition of the veins on the upper and lower surfaces of the leaf. If there are flowers or fruits, it can be distinguished even more reliably. Ternstroemia gymnanthera has a sex system that is quite rare among plants, with individuals that produce only hermaphroditic flowers (hermaphroditic plants) and individuals that produce only male flowers (male plants). This is called "male-flowered, hermaphroditic-flowered, dioecious." This is thought to have evolved to counteract the disadvantages caused by inbreeding called "inbreeding depression," but it is a sex system that is still shrouded in mystery. The fruit is also mysterious; it is known to be eaten by birds and its seeds dispersed, but when ripe it only turns red and does not contain water like a berry. Moreover, when ripe, the pericarp dries out further and loses its shape, exposing the seeds. And now the seeds are red, attracting attention. The fact that they turn red despite being dry and lacking nutrients suggests that they are mimicking nutritious fruit to deceive birds. However, the reason why the fruit changes shape after turning red, and why the seeds also turn red, is still not well understood. Perhaps a different type of bird visits. This article will explain the classification, pollination ecology, and seed dispersal of Ternstroemia gymnanthera.

What are the differences between Ternstroemia gymnanthera, Eurya japonica, and Cleyera japonica?

Ternstroemia gymnanthera, also known as Mokkoku, is an evergreen tree that grows in relatively dry areas near the coast, distributed throughout Japan (including the southwestern islands of Honshu, west of the Kanto region), Shikoku, Kyushu, the Ryukyu Islands, the southern Korean Peninsula, Taiwan, China, and extending from Southeast Asia to India (Kitamura & Murata, 1979; Mogi et al., 2000). In Japan, it has been commonly used as a garden tree due to its resistance to diseases and pests, its beautiful leaves, and its well-formed shape. It belongs to the family Cleyera.

The family Cleyraceae also includes the genera Eurya and Cleyera (Kanagawa Prefecture Flora Survey Association, 2018). However, while Eurya has serrated leaves and Cleyera does not have leaves clustered at the branch ends, Ternstroemia gymnanthera has serrated leaves and its leaves are clustered at the branch ends, which are clear differences, so it may be less likely to get confused.

What are the differences between Eurya japonica, Eurya japonica, and Sakaki? We'll explain how to distinguish between similar species! Do they bloom in early spring because they rely on bees and flies for pollination?

Hisakaki, Hamahisakaki, and Sakaki all belong to the family Cleyera (or Theaceae). Hisakaki and Sakaki, in particular, have been considered "yorishiro" (objects that house divine spirits) in Shintoism since ancient times and have been traditionally cultivated in Japan. However, their similar names may often lead to confusion...

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What are the differences between Ternstroemia gymnanthera, Pittosporum tobira, Rhaphiolepis indica, and Ilex crenata?

What might be more confusing are the species that belong to a completely different group but have entire leaves and are used as garden trees. Typical examples include Pittosporum tobira, Rhaphiolepis indica, and Ilex crenata.

Pittosporum tobira, also known as sea laurel or door tree, is distributed in Honshu, Shikoku, Kyushu, and the Ryukyu Islands of Japan, as well as in southern Korea. It is an evergreen shrub or small tree that grows naturally in coastal forests and forest edges, and also escapes cultivation into inland broad-leaved evergreen forests. In Japan, it is planted in coastal sand dune forests and gardens. It belongs to the Pittosporaceae family.

Rhaphiolepis indica var. umbellata, also known as Indian hawthorn, is an evergreen shrub distributed in Honshu, Shikoku, Kyushu, the Ryukyu Islands, and the Ogasawara Islands of Japan; as well as in Korea, China, Taiwan, and Southeast Asia, growing near the coast. It is commonly planted in parks and other public spaces. It belongs to the rose family. While there are various varieties of Indian hawthorn, the one most often confused is Rhaphiolepis indica f. ovata, which has leaves without serrations.

Ilex integra, also known as Japanese holly (Ilex integra), is an evergreen tree distributed in Honshu (south of the Tohoku region), Shikoku, Kyushu, and the Ryukyu Islands of Japan, growing in evergreen broad-leaved forests. It belongs to the family Aquifoliaceae.

How can we distinguish between these and other species of Japanese holly?

The best way to distinguish them based solely on their leaves is that the petioles of Ternstroemia gymnanthera are usually bright red (Hayashi, 2014). Pittosporum tobira has green petioles, and Ilex crenata has green or inconspicuous purple petioles. Rhaphiolepis indica can turn red, but this is not uniform and varies depending on the position of the leaf, and it is often green.

Furthermore, in Ternstroemia gymnanthera, the veins on the underside of the leaves are barely visible. However, with the exception of Ilex crenata, Pittosporum tobira and Rhaphiolepis indica have clearly visible veins on the underside of their leaves.

If we consider them individually, in Pittosporum tobira, the leaf margins usually curl towards the underside of the leaf, and the veins on the underside of the leaf are clearly visible, whereas this is not the case with Ternstroemia gymnanthera.

In Rhaphiolepis indica, there are differences between individual leaves; some have serrations, and the veins on the underside of the leaves are clearly defined, whereas this is not the case with Ternstroemia gymnanthera.

In holly (Ilex crenata), the veins are not very prominent on the upper surface of the leaves, and the tips of the leaves protrude slightly, but this is not the case with Ternstroemia gymnanthera (Turkish holly).

By considering all of the above factors, you should be able to distinguish between them.

I will omit the detailed morphology of the flowers and fruits, but as you can see in the photos, they are completely different because they belong to different families. The mature fruits of Ternstroemia gymnanthera and Pittosporum tobira expose the seeds, but in Ternstroemia gymnanthera, the fruit splits irregularly to expose the seeds, while in Pittosporum tobira, it splits regularly into three lobes to expose the seeds. If you check the fruit, you can definitely distinguish between them.

Are there any other similar species?

The distinctions between species in the genus Ilex, which are closely related to Ilex crenata, are explained in a separate article.

What are the differences between Ilex rotunda, Ilex crenata, Ilex serrata, and Ilex serrata? An explanation of how to distinguish between similar species.

Ilex rotunda, Ilex crenata, Ilex serrata, and Ilex serrata all belong to the Ilex genus of the family Aquifoliaceae. They not only grow in evergreen broad-leaved forests but are also frequently seen planted in parks and gardens, making them extremely familiar and common evergreen trees in Japan. They share thick leaves and beautiful red fruits...

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Please see our separate article for information on the differences between species of Rhaphiolepis indica (including Ternstroemia gymnanthera). Although Ternstroemia gymnanthera has a somewhat confusing name, it is a relative of Rhaphiolepis indica and is unrelated to Ternstroemia gymnanthera.

What are the differences between Rhaphiolepis indica, Rhaphiolepis umbellata, and Ternstroemia gymnanthera? An explanation of how to distinguish between similar species.

Rhaphiolepis indica, Rhaphiolepis umbellata, and Rhaphiolepis ternata all belong to the genus Rhaphiolepis in the family Rosaceae. While they naturally grow on coastlines, they are frequently seen planted in urban areas. However, the classification of the genus Rhaphiolepis is complex even at the species level, and there are many other species besides the three mentioned above...

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What is the structure of a Ternstroemia gymnanthera flower?

The flowering period of Ternstroemia gymnanthera is from June to July, blooming from early summer to summer (Mogi et al., 2000). Flowers about 1.5 cm in diameter hang downwards in the leaf axils. The flowers are white, later turning yellowish. The narrow, oblong petals, 8-10 mm long, open flat, and there are numerous stamens. There are male and hermaphroditic flowers. In male flowers, the stamens are arranged in three rows and have a lot of pollen, and the pistil is small and reduced. In hermaphroditic flowers, the stamens are arranged in one row and have less pollen, and one pistil can be seen.

Why did the unusual sex system "male flowers, hermaphrodite flowers, dioecious plants" come about?

As mentioned above, the gender of the Japanese holly has some distinctive characteristics.

This means that there are individuals that produce only hermaphroditic flowers ( hermaphroditic plants) and individuals that produce only male flowers (male plants). In other words, it's a world where both hermaphrodites and only males exist.

This is called androdioecy, or dioecy of male and hermaphroditic flowers on separate plants. The opposite case, where some plants produce only hermaphroditic flowers and others only female flowers, is difficult for humans to understand, but it is relatively well known in the plant world (Maki & Yahara, 1993). Dioecy of male and hermaphroditic flowers is an extremely rare case in plants, and only a handful of organisms exist in the world (Charlesworth, 1984)!

Why do they employ such a sexual system?

This is a very difficult topic. One theory suggests that originally, plants only existed as individuals that produced only hermaphroditic flowers, but for some reason, if individuals with similar genes come together, inbreeding can occur, resulting in the production of very weak offspring (this is well known in human history and is called inbreeding depression).

In such a situation, if a plant were to produce only male flowers and focus solely on pollen production, the same thing would happen if the pollen were carried by insects to the flowers of nearby plants. However, if it were lucky enough to be carried far away, it might be able to produce healthy offspring. This is thought to be the reason why male plants are born. However, even if this is the case, the detailed conditions are still not fully understood. It would be interesting if this complex mystery were to be researched and solved someday.

Do male flowers, which are full of pollen, attract bees?

For the reasons mentioned above, it can be observed that male flowers, in particular, have a large amount of pollen, suggesting that the flowers of the Japanese holly (Turkish japonica) attract bees that carry a lot of pollen.

However, my research did not yield any papers that specifically listed the visiting insects. I did find four photos on the internet of European honeybees (Apis mellifera) visiting flowers in Japan, so I suspect that many of the bees are indeed there for pollination.

Even though the flower shapes differ significantly between *Tetramorium laevigata* and *Tetramorium dentata*, which are related species to *Tetramorium*, it has been confirmed that bees visit them and carry pollen using a special method called "vibration pollination" (Bittrich et al., 1993). This further supports the prediction that bees will visit the flowers.

The fruit of the Japanese holly (Mokkoku) is a capsule, yet it's dispersed by birds!?

The fruit of Ternstroemia gymnanthera is a capsule. It is spherical, 1-1.5 cm in diameter, and ripens red in October and November. The pericarp is fleshy and splits open irregularly when ripe, releasing orange-red seeds. The seeds are obovate, about 7 mm long.

How is seed dispersal carried out?

Several Japanese studies have shown that the fruits of the Japanese holly (Turkish japonica) are eaten by birds such as the Oriental Turtle Dove (Streptopelia orientalis), the Daurian Redstart (Phoenicurus auroreus), the Varied Tit (Sittiparus varius), and the Carrion Crow (Corvus corone) (Fujita and Shinohara, 2001), as well as mammals such as the Yakushima Macaque (Macaca fuscata yakui) (Otani, 2005). However, considering its size and habitat, it is thought that it is more often eaten by birds than mammals. In addition, there have been observations of thrushes, flycatchers, and the Japanese White-eye (Zosterops japonicus) eating the fruits (Kanouchi, 2021), and a study in Korea has also recorded that it is eaten by the Brown-eared Bulbul (Hypsipetes amaurotis) (Kim et al., 2015).

By the way, the fruit of the Japanese holly is a little strange. It turns red when ripe, which is clearly to attract animals and get them to eat it, but it doesn't contain much water like a berry. Moreover, when it ripens, the pericarp dries out and loses its shape, exposing the seeds. And then the seeds turn red to attract animals.

It's still unclear how this is perceived by birds that eat the fruit of the Japanese holly tree. However, considering this progression, there may be two phases: one that appeals to birds that eat the whole fruit, and another that appeals to birds that eat only the seeds.

In the phase where the fruit is intended to appeal to birds that eat it whole, the thin peel makes it unsuitable as a food source for birds. In other words, it seems that the Japanese holly (Mokkoku) deceives birds by mimicking ordinary fruits by turning red (Ueda, 1999).

It's unclear to what extent the phase of appealing to birds that only eat seeds contributes to seed dispersal. In the case of seeds, unless the seed coat is made quite strong, there is a risk that it will simply be digested by birds and used for nutrition.

As you can see, there are many mysteries surrounding both the flowers and fruits of this plant. When you come across a Japanese holly tree, try observing it carefully to see what animals it interacts with; you might discover something new.

References

Bittrich, V., Amaral, MC, & Melo, GAR 1993. Pollination biology of Ternstroemia laevigata and T. dentata (Theaceae). Plant Systematics and Evolution 185(1): 1-6. ISSN: 0378-2697, https://doi.org/10.1007/BF00937716

Charlesworth, D. 1984. Androdioecy and the evolution of dioecy. Biological Journal of the Linnean Society 22(4): 333-348. ISSN: 0024-4066, https://doi.org/10.1111/j.1095-8312.1984.tb01683.x

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