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...

ecological-information.com

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...

ecological-information.com

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

Parnassia palustris, Parnassia japonica, and Parnassia japonica are all perennial herbs belonging to the genus Parnassia in the family Celastraceae. Their names are similar, and their leaves and flowers are also similar in appearance, which can make identification difficult. These three species can be distinguished mainly by the number of lobes in the staminodes of the flower. Staminodes are a special structure found in the genus Parnassia. The flowers are white, have five petals, and grow singly at the tip of the stem. The fruit is a capsule. This article will explain the classification and morphology of Parnassia palustris, Parnassia japonica, and Parnassia japonica.

What are Parnassia palustris, Parnassia japonica, and Parnassia japonica?

Parnassia palustris var. palustris, also known as Umebachisou (Plum Blossom Grass), is a perennial herb distributed in Hokkaido, Honshu, Shikoku, and Kyushu in Japan; as well as Taiwan, Northeast Asia, Sakhalin, and the Kuril Islands, growing in sunny, damp areas in mountainous regions (Ohashi et al., 2016). var. multiseta is a synonym (former scientific name).

Parnassia palustris var. tenuis, also known as small plum blossom grass, is a perennial herb that grows in alpine regions and is distributed in Hokkaido and northern Honshu in Japan; Siberia, Central Asia, the Caucasus, the Middle East, Europe, and North America (RBG Kew, 2023).

Parnassia alpicola, also known as Himeumebachisou (dwarf plum blossom grass), is a perennial plant distributed in Honshu, Japan (northeast to central Japan), growing in damp grasslands and former snowfields in high mountains.

Both are perennial herbs belonging to the genus Parnassia in the family Celastraceae. Their names are similar, and morphologically they share many similarities, such as heart-shaped basal leaves with entire margins and long petioles, and solitary flowers at the tip of the stem with five white, entire petals. This can sometimes make identification difficult.

What are the differences between Parnassia palustris, Parnassia japonica, and Parnassia japonica?

These three types can be distinguished primarily by the number of lobes in the staminodes of the flower.

Staminodes are thread-like structures found on the petals, separate from the stamens. They typically consist of five structures, each with a thread-like lobe at the tip, and sometimes have small, yellow, round glands (glands).

First, the three types can be broadly classified based on the difference between Parnassia palustris and Parnassia japonica, which have seven or more lobes in their staminodes and a yellow gland (round granule) at the tip, and Parnassia japonica, which has fewer lobes in its staminodes, ranging from three to five (rarely six to eight), and lacks a yellow gland at the tip.

Koumebachisou is a high-altitude variety of Umebachisou, so they are very similar.

Regarding Parnassia palustris and Parnassia japonica, the difference lies in the number of lobes in the staminode stamen and the yellow glands attached to their tips: Parnassia palustris has 12 to 22 lobes, while Parnassia japonica has 7 to 11.

With the above information, you can easily distinguish them if they have flowers.

Incidentally, there was once a classification called Ezo-umebachisou, but it is now considered a synonym (former scientific name) of Umebachisou and is not specifically distinguished from it.

Furthermore, regarding Parnassia palustris and Parnassia japonica, there is a view abroad that Parnassia japonica is a synonym of Parnassia palustris and that there is no special distinction between them (RBG Kew, 2023).

Parnassia palustris var. yakusimensis is a dwarf variety of Parnassia palustris distributed on Yakushima Island. It is delicate overall and has small flowers. The leaves are ovate to broadly ovate, about 1 cm long and wide (Parnassia palustris has leaves about 1.5-4 cm long and wide).

Parnassia palustris var. izuinsularis is distributed in the Izu Islands and is known as "Kozushima Parnassia".

What is the structure of a flower?

Parnassia palustris flowers from August to October. The flowers are white, 2-2.5 cm in diameter, and bear a single upward-facing flower at the top of the stem. They have five petals that are broadly ovate to elliptical with prominent green parallel veins. There are five staminodes, each with 12-22 lobes at the tip and a yellow gland at the end.

Koumebachisou (Parnassia palustris) blooms from July to September. It closely resembles Umebachisou (Parnassia palustris), but is smaller overall, with flowers about 1 cm in diameter. Its staminodes are divided into 7 to 11 lobes.

Parnassia palustris flowers from August to September. Each flower is white, 8-10 mm in diameter, and borne singly at the tip of the flower stalk. The petals are five in number, broadly ovate with a blunt tip, 4-6 mm long, with a distinct claw at the base, and open flat when in bloom. The calyx tube is short, and the calyx lobes are five in number, lanceolate-ovate with a blunt tip, about 2.5 mm long. There are 10 stamens, about 3 mm long, with circular anthers that are grayish-brown before dehiscence. The staminodes are 3-5 (rarely 6-8) lobed, and the tips of the lobes lack glands.

What is the structure of the fruit?

The fruit is a capsule, which is common to all species in the Parnassia genus.

The capsules of Parnassia palustris are 1-1.2 cm long.

The capsule of Parnassia palustris is 5-6 mm long. The seeds are numerous, oval-shaped, and about 1 mm long.

References

Ohashi, Hiroyoshi; Kadota, Yuichi; Murata, Hitoshi; Yonekura, Koji; and Kihara, Hiroshi. 2016. Wild Plants of Japan (Revised New Edition, Vol. 3 Rosaceae to Meliaceae). Heibonsha, Tokyo. 604pp. ISBN: 9784582535334

RBG Kew. 2023. The International Plant Names Index and World Checklist of Vascular Plants. Plants of the World Online. http://www.ipni.org and https://powo.science.kew.org/

The family Saxifragaceae consists of herbaceous plants. Leaves are alternate or opposite, simple or compound. Most are deciduous, but some are evergreen. Stipules are present or absent. Inflorescences are cymose, sometimes racemes or panicles. Flowers are bisexual, dioecious, or dioecious, radially or bilaterally symmetrical, pentamerous, rarely tetramerous. Sepals number 4-5, and petals are the same number or absent. Stamens are the same number as sepals, or twice as numerous. Staminodes are absent. Carpels and styles are usually 2, rarely 3. The base of the ovary is a unilocular paramembrane placenta or a 2locular axial placenta. Fruit is a capsule. Seeds are small, numerous, and contain endosperm. Species within the genus Saxifragaceae are often similar, but intergeneric species are often dissimilar. This family underwent a major reorganization in the APG system. Of the herbaceous plants formerly belonging to the Saxifragaceae family, the genus Penthorum became the independent family Penthoraceae, and the genus Parnassia became the family Celastraceae. Globally, it is abundant in the Northern Hemisphere, particularly in North America, East Asia, and the Himalayas, and is also distributed in South America. The APG system recognizes 33 genera and 640 species, with approximately 60 species in 10 genera found in Japan. The pollinating insects of this family are mainly flies, especially members of the Empididae and Syrphidae families, but honeybees, solitary bees, bumblebees, butterflies, ants, and beetles are also said to visit (Konarska, 2014). Tanaka (1983) has researched pollinating insects in Japan, but I have not yet seen it.

This article provides a comprehensive, field guide-style introduction to plants belonging to the Saxifragaceae 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. 1371 Saxifraga stolonifera

This perennial herb propagates by sending out long, thread-like red stolons in all directions, each bearing new shoots at its tip. The leaves and stems are covered in coarse reddish-brown hairs. It flowers from May to June. The flower stalks grow upright in conical cymes, reaching a height of 20-50 cm. The flowers consist of five white petals. Of the five petals, the three upper ones are ovate, about 3 mm long, tinged with pale pink, and have dark red markings and dark yellow spots at the base. The two lower petals are unspotted and 1-2 cm long. They have a dark yellow floral disc. It is distributed in Honshu, Shikoku, Kyushu, and China. It grows in clusters in shady areas near human settlements, on stone walls and rocks near water. It is a useful plant and has been cultivated since ancient times. The asymmetrical flowers are characterized by pink anthers and a diverse distribution of dark yellow and dark red flavonoid pigments on the petals, forming symmetrical spots on the petals known as nectar guides that lead pollinating insects to the nectar (Konarska, 2014). The stamens are initially arranged almost parallel to the petals (Tanaka and Hirano, 2000). However, upon maturation and entering the male phase, they stand upright, move forward, and release pollen. They move in a fixed order, releasing pollen one after another, and once they have finished releasing pollen, they enter the female phase, and the pistil begins to elongate. Tanaka and Hirano (2000) include a photograph of a hoverfly (Syrphidae japonica) visiting the flowers, and it is believed that syrphidae and bees also visit them.

No. 1372 Haruyukinoshita (Saxifraga nipponica)

This is a perennial herb. The leaves are circular with a heart-shaped base and shallowly lobed margins (13-17 lobes). The petioles and both sides of the leaves are covered with white glandular hairs. The flower stalks are 20-30 cm tall, and the flowering period is from April to May. The petals are white, with the three upper petals being ovate with yellow spots at the base, while the two lower petals are unspotted, 1-2.5 cm long, and acute at the tip. There is a dark yellow floral disc. It is distributed in Honshu (Kanto, Chubu, and Kinki regions). It grows on slightly damp rocks along streams in lowlands to lower mountainous areas, sometimes forming colonies. Fudōjiri on Mt. Ōyama marks the easternmost point of its distribution in Japan. This species is distributed in the Hokuriku region, isolated from the Tanzawa Mountains, and lacks distribution inland, exhibiting a discontinuous distribution. Those found in the Tanzawa Mountains are smaller than those on the Sea of Japan side.

No. 1373.1 Saxifraga fortunei var. jotanii

This is a perennial herb. The leaves are shallowly lobed, thick in texture, and have many hairs on the leaf blade and petiole. It flowers from October to January. The flower stalks and stems have long glandular hairs. It is distributed only in Chiba Prefecture and the Izu Islands. In Kanagawa Prefecture, there is a specimen that was collected in Zushi a long time ago, but it has not been confirmed in subsequent surveys, and it is classified as extinct in the "Kanagawa Red Data Book 06".

No. 1373.2 Saxifraga fortunei var. obtusocuneata f. minima

This is a dwarf variety of Saxifraga fortunei var. obtusocuneata. Its leaves are very small, measuring 4-15 mm in length and 5-16 mm in width. It flowers from August to October. It is an endemic species of Japan, distributed in Kyushu (Yakushima), and grows on damp rocks in high-altitude areas.

No. 1374 Saxifraga cortusifolia

This is a perennial herb. The leaves are 7 to 10 lobes and somewhat palmate. Needle-shaped oxalate crystals are present in the leaf tissue. It flowers from September to November. The petals resemble those of Saxifraga stolonifera, with yellow spots on the three upper petals and long, unspotted petals on the two lower petals. The anthers are orange-yellow. It has a yellow floral disc. It is distributed in Honshu (west of Kanto), Shikoku, and Kyushu. It grows on rocky cliffs in mountainous areas.

No. 1374.1 Purple Saxifraga cortusifolia f. atropurpurea

A variety of Saxifraga fortunei with dark purple leaves.

No. 1375 Saxifraga sendaica

This perennial herb (Fukuoka Prefecture Red Data Book 2014) has stems 5-15 cm tall with several leaves at the top. The leaves are thick and glossy, with ovate to ovate-circular blades reaching 12 cm in length and shallowly lobed edges. The petioles are long and have stipules at the base. It flowers in October in corymbose inflorescences 7-10 cm in diameter, with five white petals, the lower one or two of which are longer than the others. It is distributed in Honshu (Nara, Wakayama), Shikoku (Tokushima), and Kyushu (Nagasaki, Kumamoto, Miyazaki), growing on rocky cliffs in deep mountains. It is listed as Endangered II in the Ministry of the Environment's Red Data Book.

No. 1390 Chrysosplenium japonicum

This is a perennial herb. It does not produce stolons. After flowering, bulbils form at the base of the stem. The basal leaves are round with 7 to 11 flattened serrations along the margin. The flowering stems are 10 to 20 cm tall and pale yellowish-green. The stem leaves are alternate and round with long petioles. It flowers from March to April. The calyx lobes are green, spreading, semi-circular, and erect after flowering. There are 4 to 8 stamens. The anthers are yellow. The seeds are ovate, 0.6 to 0.7 mm long, with one ridge. The surface appears smooth to the naked eye, but under magnification with a microscope, minute papillary projections can be seen. It is distributed in Hokkaido (southwest), Honshu, Shikoku, Kyushu; Korea; and China (northeast), growing in clusters in moist woodlands, forest edges, and rice paddy ridges in lowlands to lower mountainous areas.

No.1392.a Heuchera sanguinea

Perennial herb (Flora of North Ameica). Stemless, with branched stumps. Flower stalks are 20–40 cm long, sometimes with long-stalked glands. Petioles have long-stalked glands. Leaf blades are kidney-shaped to orbicular, shallowly 5–7-lobed, 2–5.5 cm long, with a cordate base, rounded lobes, toothed margins, and an acute to obtuse apex. The underside has long-stalked glands on the veins, while the upper surface is glabrous or sparsely covered with long-stalked glands. Flowering occurs from March to October. Inflorescences are moderately dense to diffuse. The hypanth is weakly bilateral to radially symmetrical, 2.5–2.8 mm separated, dark pink to red, broadly bell-shaped or urn-shaped, 4–8 mm long, with short-stalked glands at the base and sparsely covered with long-stalked glands at the top. Sepals are spreading, dark red at the apex, equal in length, 2–3 mm long, with oblong or rounded apex. The petals are spreading, pink or cream-colored, narrowly oblanceolate, undivided, 1.2–1.8 mm long (shorter than the sepals), and entire. The stamens are not protruding, 1.5–3 mm long. The style is not protruding, 1.5–3 mm, 1.5–2 mm long, and 0.1 mm in diameter. The capsule is ovate, 4.5–6 mm long, with a spreading beak and no papillae. The seeds are dark brown, elliptical, 0.5–0.6 mm long, and have blunt spines. It is distributed in southwestern North America and northern Chihuahua, Mexico, growing on rocks in moist, shady places. It is cultivated as an ornamental plant in various countries, including Japan.

No.1392.b Heuchera micrantha 'Palace Purple'‘

As its scientific name suggests, it is Heuchera micrantha. It is a perennial herb (Flora of North America). It is stemless, with branched stumps. The flower stalks are 6–570 cm long, with short to long stalked glands or glabrous and sticky. The petioles are glabrous or sparsely to densely with short to long stalked glands. The leaf blades are orbicular to polygonal, 5–7 (–9) shallow to deeply lobed, 2.5–10 cm long, with a cordate base, rounded lobes, toothed margins, an orbicular to obtuse apex, glabrous or with short to long stalked glands and sticky. The inflorescence is diffusive. The hypanth is radially symmetrical, with separate parts less than 1.5 mm, greenish-white, often tinged with red, obconical to hemispherical to broadly conical to campanulate, 1–4.9 mm long, with long stalked glands, sometimes with short stalked glands at the base. The sepals are spreading to nearly erect, with green or red tips, equal in length, 0.5–1.8 mm, and rounded to acute to mucronate at the apex. The petals are often coiled, white or pale pink, oblanceolate (with narrow claws), undivided, 1.6–3.3 mm long (2–3 times the length of the sepals), and entire. The stamens are protruding, less than 3 mm long. The style is protruding, less than 2 mm long, 0.2–4.2 mm in length, and less than 0.1 mm in diameter. The capsule is ovate, 3–8.5 mm long, with a spreading beak and no papillae. The seeds are black, broadly elliptical (uncurved), and 0.5–0.8 mm long. There are 5 varieties. In Japan, it is often confused with Heuchera bells, but while Heuchera bells has red calyxes and stamens and pistils shorter than the petals, this species has milky white calyxes and stamens and pistils that protrude beyond the petals. It can be distinguished from Heuchera villosa by its rounded leaf lobes. 'Palace Purple' is a horticultural variety with purple leaves. It is distributed in North America, and many varieties grow in mixed evergreen forests with limestone or serpentine soil. It is cultivated as an ornamental plant in various countries, including Japan.

References

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

Konarska, A. 2014. Micromorphology and anatomy of flowers and nectaries of Saxifraga stolonifera L. Acta Agrobotanica 67(4): 3-12. ISSN: 0065-0951, https://doi.org/10.5586/aa.2014.054

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

Tanaka, Tadatsugu. 1983. Insects that visit flowers of plants in the Saxifragaceae family. Journal of the Toyama Prefectural Biological Society 23: 13-29.