Akebia, three-leaved akebia, five-leaved akebia, and Stauntonia hexaphylla all belong to the Akebia family. They are climbing plants with palmately compound leaves, and their most distinctive feature is that male and female flowers bloom separately. Akebia and three-leaved akebia are particularly famous for the edible white, gelatinous pulp inside their opened fruits. While they are associated with nostalgic rural flavors from childhood memories, few people may be able to distinguish between them.They can generally be distinguished by the shape of their leaves, but differences also appear in the shape of their flowers and the degree to which their fruits dehisce.Flowers rely on cross-pollination by insects, and the size difference between male and female flowers is known to be a strategic feature. Seed dispersal is also interesting, as it depends on a variety of animals, including mammals, birds, and ants. This article will explain the classification, morphology, and ecology of the Akebia family.
- What are Akebia, Mitsuba Akebia, Goyou Akebia, and Mube?
- What are the differences between Akebia, Mitsuba Akebia, Goyou Akebia, and Mube?
- What are the differences in how Akebia, Mitsuba Akebia, Goyou Akebia, and Mube are used?
- How did pollination work? Was it to deceive insects with large female flowers?!
- How did they disperse their seeds? They used all sorts of methods: mammals, birds, ants, you name it!?
- References
What are Akebia, Mitsuba Akebia, Goyou Akebia, and Mube?
Akebi (Kidori, Togusa, Yamahime, Yamaonna) Akebia quinata This deciduous climbing woody plant is distributed in Honshu, Shikoku, and Kyushu in Japan; the Korean Peninsula; and China, and commonly grows in forest edges in hilly and mountainous areas. The Japanese name is said to originate from the fact that its fruit splits open ("akemi" meaning "open fruit").
Mitsuba akebi (Mitsubagi-dori/Mitsuba-dori grass) Akebia trifoliata subsp. trifoliata This deciduous climbing woody plant is distributed in Hokkaido, Honshu, Shikoku, and Kyushu in Japan, as well as in China, and commonly grows in forest edges in hilly and mountainous areas.
Japanese akebia (Akebia quinata) Akebia x pettaphylla This is a natural hybrid of Akebia quinata and Akebia trifoliata, and is a deciduous climbing woody plant that is rarely found in places where Akebia quinata and Akebia trifoliata grow together.
Mube (Ikuko, Wild Melon) Stauntonia hexaphylla It is also known as Tokiwaakebi. It is a deciduous climbing woody plant distributed in Honshu (west of the southern Kanto region), Shikoku, Kyushu, and the Ryukyu Islands in Japan; the Korean Peninsula; and China. It grows at the edges of forests and is often planted as a hedge in parks and private homes. Makino suggests that the origin of the Japanese name comes from the fact that its fruit was offered to the imperial court, and that this was called Ohonihe, which became Ohomube, and then Mube (Kato and Nakamura, 1971). However, the basis for this argument is not very clear.
All of these plants belong to the Akebia family, are climbing plants, have palmately compound leaves, and are monoecious, but a key characteristic is that their flowers are unisexual, meaning that male flowers grow separately.
Of the four species, three, excluding Stauntonia hexaphylla, belong to the genus Akebia. Their most distinctive feature is that when ripe, their fruit splits open, exposing a liquid, fleshy interior.
This fruit is unique, and its name varies depending on the source. Although it is a "follicle (a fruit consisting of one carpel that dehisces along the internal or external suture)" (Shimizu, 2001), it is sometimes called a "berry" because its interior is a liquid that animals can eat (Mogi et al., 2000). Since 3 to 5 fruits can sometimes be clustered together, in this case it is called an "aggregate fruit," and is sometimes referred to as an "aggregate follicle" or "aggregate berry."
In Japan, there has been a long-standing tradition of eating this fruit, and it is associated with people's memories of the taste of the countryside from their childhood. There are also cultivated varieties of Akebia trifoliata, which are sometimes sold commercially.
However, several closely related species are known, and all of them are edible, so perhaps few people can correctly distinguish between them.
In particular, Akebia trifoliata has compound leaves with five leaflets, but Akebia quinata also has five leaflets, which can be confusing. Some companies even sell Akebia quinata as "Akebia trifoliata with five leaflets."
What are the differences between Akebia, Mitsuba Akebia, Goyou Akebia, and Mube?
As a fundamental point, Akebia quinata, Akebia trifoliata, and Akebia quinata belong to the Akebia genus, while Stauntonia hexaphylla belongs to the Stauntonia genus (Kanagawa Prefecture Flora Survey Association, 2018).
Therefore, there is a significant difference in form.
In Akebia, Akebia trifoliata, and Akebia quinata, the leaves are deciduous, the sepals are three cup-shaped, the stamens are six and free, and the fruit dehisces, whereas in Stauntonia hexaphylla, it is evergreen, the sepals are six in number (three outer ones are lanceolate and three inner ones are linear), the stamens are six and fused, and the fruit does not dehisce.
While there are many factors to consider, the biggest difference is whether the plant is deciduous or evergreen. In other words, Akebia, Akebia trifoliata, and Akebia quinata lose their leaves in winter, resulting in soft, thin, light green leaves, while Stauntonia hexaphylla retains its leaves even in winter, giving it sturdy, hard, dark green leaves. This can be observed by examining the leaves.
Another easily noticeable difference, even just looking at the leaves, is that in Stauntonia hexaphylla, the veins are prominent on both the upper and lower surfaces of the leaves, and the number of leaflets can range from three in young trees to five to seven in mature trees. These features are entirely unique to Stauntonia hexaphylla and are not found in the Akebia genus.
It's easy to mistakenly think that Akebia plants have multiple leaves, but these are palmate compound leaves, meaning that what was originally a single leaf has divided into 3 to 7 leaflets. These divided parts that look like a single leaf are called "leaflets."
Another point to note is that while botanical guides state that the fruit of Stauntonia hexaphylla does not split open, actual photographs show that it does split open slightly, though not as much as in the Akebia genus.
Of the remaining three species, Akebia trifoliata is a hybrid of Akebia quinata and Akebia quinata, and therefore exhibits intermediate characteristics (Kanagawa Prefecture Flora Survey Association, 2018; Yoshizawa and Arase, 2024; Hayashi, 2025).
Focusing on the number of leaflets, Akebia and Akebia trifoliata usually have five leaflets, while Akebia quinata has only three. This difference is reflected in its Japanese name.
However, since Akebia quinata can occasionally have 3 to 4 leaflets, you need to check for multiple leaflets.
If we focus on the serrations of the leaflets, we can see that while Akebia trifoliata and Akebia quinata usually have serrations, Akebia quinata does not.
However, this is also Akebia quinata, and some of the current year's branches in the upper layers lack serrations, so it is necessary to check multiple leaves.
Focusing on the flowers, in Akebia quinata, the male flowers are sparsely arranged and the sepals are pale purple, while the female flowers have long stalks and protrude from the male inflorescence. In contrast, in Akebia trifoliata and Akebia quinata, the male flowers are densely arranged and the sepals are dark reddish-purple, while the female flowers have somewhat shorter stalks and do not protrude from the male inflorescence.
Based on the above, I believe you can definitely distinguish between the four types.
What are the differences in how Akebia, Mitsuba Akebia, Goyou Akebia, and Mube are used?
The main use of Akebia and Mitsuba Akebia is, of course, for their sweet fruit. The fruit ripens in the autumn (around September to October).
In addition to consuming the wild fruit, there are also cultivated varieties of Akebia trifoliata for fruit production (Matsumoto et al, 2022; Yoshizawa & Arase, 2024).
The fruit consists of a pericarp and a white pulp (placenta) that encloses the black seeds, and this pulp is edible (Fruit Tree Horticulture Laboratory, Faculty of Agriculture, Yamagata University, 2020).
The typical way to eat it is to pick the fruit, eat the white gelatinous substance (placenta) as is, taste the flesh, and then spit out the seeds inside.
In rural areas, it has long been a popular snack for children playing in the mountains, and it is sometimes described as a "rare fruit that evokes nostalgia," adding color to fond childhood memories (Yoshizawa & Arase, 2024).
The fruit is sweet and juicy, and rich in nutrients such as sugars, proteins, amino acids, vitamins, and minerals (Huang et al., 2022).
Grapes are highly regarded nutritionally, containing a high amount of various vitamins such as beta-carotene, vitamin B, and vitamin C (108-930 mg/100 g), which is higher than apples, grapes, and bananas. They are also rich in minerals such as potassium (3.2-4.9 mg/g), magnesium (1.00-1.51 mg/g), and calcium (0.47-0.49 mg/g), as well as amino acids, including all eight essential amino acids.
The peel became a topic of discussion when YouTuber Hikakin, not knowing how to eat it, discarded the flesh and ate the peel raw, describing it as bitter and unpleasant (J-CAST News Entertainment Team, 2025). However, it is not edible raw.
However, the peel can also be eaten after being boiled or stir-fried, and dishes such as "stir-fried akebi peel with miso" are known (Fruit Tree Horticulture Laboratory, Faculty of Agriculture, Yamagata University, 2020).
The young shoots can be used in dishes such as blanched greens, salads, soups, and stir-fries (Takahashi, 2003). In the Tohoku region, the young shoots of Akebia trifoliata are called "kinome" (tree buds) because they contain less bitterness than Akebia quinata, and were used in "kinome-meshi" (tree bud rice).
In addition, it is cultivated for ornamental purposes in horticulture (Huang et al., 2022), and the outer bark of the thick vine stems is removed and sun-dried, which is calledKidoriIt is called " and has diuretic, anti-inflammatory, analgesic, cardiac stimulant, antibacterial, and antioxidant effects, and has been used as a herbal medicine effective against nephritis, urethritis, cystitis, etc. (Maciąg et al., 2021).
Akebia quinata does not produce fruit, so it is not used for food.
While the fruit of the Stauntonia hexaphylla is edible, it is small and does not split open completely, making it difficult to eat, and therefore it is rarely found in the market.
However, Makino suggests that the origin of the Japanese name is that the fruit was offered to the imperial court, and that this was called "Ōhonihe" (大供), which became "Ōmube" (苞苴), and then "Mube" (Kato and Nakamura, 1971). There is also a theory that when Emperor Tenji was presented with it, he replied, "Mube naru kana" (meaning "That is indeed true"). The veracity of these claims is quite questionable, but it seems certain that Mube was used in ancient times (Wano, 2015).
How did pollination work? Was it to deceive insects with large female flowers?!
The shape of the flowers differs greatly between the Akebia and Stauntonia genera (Kanagawa Prefecture Flora Survey Association, 2018).
In the Akebia genus, the flowering period is in spring, from April to May. Male flowers are numerous and borne at the tip of the inflorescence, with short filaments that curve inward in an arching shape, forming a spherical cluster. Female flowers are larger than male flowers, borne in small numbers at the base of the inflorescence, and have 3 to 9 oblong carpels that spread outwards. What appear to be three petals are actually modified sepals.
It has a strong scent and is sometimes called "the flower with the fragrance of chocolate" in Europe and America.
What kinds of insects visit this flower? Akebia species are self-compatible and cannot produce fruit without pollen from other individuals.
According to research on Akebia, the main pollinating insects are of the genus Carpenter bees. Lasioglossum Small, solitary wasps (bees without a caste system), such as *sp.*, and hoverflies. Epistrophe balteata(Syrphidae family), Japanese honeybee Apis cerana japonicaIt is known to belong to the family Apidae (Kawagoe & Suzuki, 2002).
While there is insufficient research on Akebia trifoliata, some believe it may be similar to Akebia quinata (Matsumoto et al, 2022). However, there are morphological differences, such as the male flowers of Akebia trifoliata being darker in color, so it has not been verified whether they are truly the same.
While the Japanese akebia (Akebia quinata) produces flowers, it does not produce fruit, so it cannot reproduce.
By the way, there's a curious difference between the male and female flowers of the Akebia genus. The female flowers are noticeably larger and more conspicuous than the male flowers. Why is this?
This is thought to be "intersexual mimicry," where female flowers mimic male flowers (Kawagoe & Suzuki, 2002; 2003). In other words, since female flowers have no stamens, they naturally have no pollen and offer no reward to pollinators, but they grow larger than male flowers to appear more attractive to pollinators in order to deceive insects into thinking "there's food here!"
Furthermore, especially in solitary bees, they will visit the more attractive-looking female flowers before moving on to the male flowers. This prevents self-pollination within the same individual by preventing pollen from the male flowers from touching the stigma of the female flowers, thus promoting cross-pollination.
As mentioned above, Akebia is self-incompatible, so this cross-pollination is thought to be for the purpose of avoiding reproductive interference (by its own pollen), rather than suppressing inbreeding (preventing inbreeding depression) (Kawagoe & Suzuki, 2005).
Surprisingly, however, hoverflies can distinguish between male and female flowers and only visit the male flowers, resulting in a situation where they steal nectar.
On the other hand, Stauntonia hexaphylla flowers in spring, from April to May, producing short racemes from the leaf axils. These inflorescences have 6 sepals and bear 3 to 7 pale yellow flowers that face downwards and have a single reddish-purple stripe on the inside (Mogi et al., 2000). There are no significant differences between male and female flowers except for the stamens and pistils.
Despite having the exact same flowering period, the reason why the male and female Stauntonia hexaphylla are identical in appearance remains unknown, unfortunately due to insufficient research on pollinating insects.
The facts above confirm that wild insects (mainly bees) produce delicious akebi fruit, both wild and cultivated. This kind of benefit is called an "ecosystem service," so if you want to eat delicious akebi, please take an interest not only in the akebi itself, but also in the natural environment that supports these insects.
How did they disperse their seeds? They used all sorts of methods: mammals, birds, ants, you name it!?
As mentioned above, the fruits of the Akebia family ripen in the autumn and are "follicles" that split open or crack, but are also called "berries" because the inside is a liquid that animals can eat.
The thick rind changes from green to red to purple as it ripens, and when it splits open, the inside is exposed, revealing black seeds encased in a white, gelatinous placenta.
Fruits that are clearly large and would be considered tasty for humans are likely to be dispersed by animal means, particularly by mammals.
In fact, the fruit of Akebia has been used by martens and raccoons (Takatsuki, 2017; 2018), and there are records of the fruit of Akebia trifoliata being used by martens, raccoons, and Japanese macaques (Takatsuki, 2017; Kumagai and Saito, 2022; Otani, 2005).
The fruits of the Stauntonia hexaphylla are also used by martens and raccoons (Takatsuki, 2017; 2019).
The slimy seed coat is thought to be adapted to slip through the teeth of animals (Okamoto, 1999).
However, there are also records of an increase in seedlings of Akebia quinata and Akebia trifoliata within goldenrod communities (Karasawa, 1978). This suggests that birds may be contributing to seed dispersal of Akebia quinata and Akebia trifoliata.
Generally, red fruits are only visible to birds and monkeys with well-developed color vision, so considering this point, it is plausible that seeds are dispersed by both mammals and birds.
Furthermore, the seeds of Akebia and Akebia trifoliata have elaiosomes. This indicates that these are parts that ants eat, and that after being eaten by animals, the seeds are excreted in their feces and then dispersed again by ants, thus contributing to ant dispersal (Nakanishi, 1988).
In the field, there have been observations of brown ants gathering around the seeds (Kusui & Kusui, 1999). In experiments where seeds were placed directly near ant nests, black garden ants and brown ants carried them away (Fujii et al., 2012).
However, unlike Akebia quinata and Akebia trifoliata, Stauntonia hexaphylla does not have elaiosomes (Kusui & Kusui, 1999).
References
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