Stauntonia hexaphyllaDecne., 1839 In: Ann. Sc. Nat. Ser. II. 12: 105 (1839), et in Arch. Mus. Par. 1: 192 or Stauntonia vine is a plant in the family Lardizabalaceae.
In Japan, it is distributed in Honshu, Shikoku, Kyushu, and Okinawa. Outside Japan it is found in South Korea. It grows wild in mountains and hills in warm regions and near the coast. Outside of its natural distribution, it is sometimes planted in gardens as shade shelves.
Its Japanese range extends from the southern Kantō region westward, and the species is also found in Taiwan and China.
In Japanese it is called Mube (ムベ, or 郁子).
Names The Japanese name mube is said to derive from the older name ōmube, associated with the traditional presentation of its fruit to the Imperial Court.
Because it resembles Akebia while remaining evergreen, the plant is also known in Japan as tokiwa-akebi (トキワアケビ, literally "evergreen akebia"). Other Japanese names include ube, as well as the regional names gube in the Isahaya area of Nagasaki Prefecture, fuyubi in the Oki Islands of Shimane Prefecture, and unbe in Kagoshima Prefecture. Other recorded names include inochinaga and kokko.
Description Stauntonia hexaphylla is an evergreen woody vine. The bark ranges from pale brown to brownish brown and bears lenticels. On mature stems, the bark becomes shallowly fissured lengthwise and may peel away. Young branches are green and have conspicuous lenticels.
The leaves are stalked and palmately compound. They usually have five leaflets, although leaves on young shoots may have three, while those on mature branches have five to seven. The leaflets are thick and leathery, dark green and glossy on the upper surface, and somewhat paler beneath. A distinctive network of veins is visible on the underside.
Flowers Flowering occurs from April to May. The species is monoecious, with separate male and female flowers occurring on the same plant. The flowers are borne in racemes from the leaf axils. Female flowers are larger than male flowers and are fragrant.
The outside of the flower is pale yellowish green, while the inner surface is dark reddish purple. Both male and female flowers lack true petals and instead have six sepals.
Fruit The fruit ripens from September to October. It is elliptical, about long, and becomes dark reddish purple when ripe.
The fruit resembles that of Akebia, but its skin is thinner and softer. Unlike the fruit of Akebia, it does not split open along the sutures of the carpels when ripe. Inside the skin is a very hard, milky-white layer. Numerous small black seeds occur within, surrounded by translucent pulp derived from the placental tissue. Sweet juice fills the spaces between the seeds.
The pulp is sweet and edible, although the seeds are firmly attached to it and can be difficult to separate when eating. In the wild, Japanese macaques eat the fruit and may contribute to seed dispersal.
Winter buds The winter buds are conical and long. They are enclosed by 10 to 16 bud scales that range from green to reddish brown. The leaf scars beneath the buds are semicircular and may appear as though the petiole has been torn away. The vascular bundle scars are indistinct.
Uses Stauntonia hexaphylla is grown as an ornamental plant and can be cultivated as bonsai or trained over trellises to provide shade. Its fruit is edible.
The plant has traditionally been valued as a fruit crop in Japan, where there is a long-standing tradition of presenting its fruit to the Imperial House of Japan. The fruit is smaller than that of many Akebia species. Although its pulp is sweet, the numerous seeds make it comparatively difficult to eat, limiting its commercial importance.
Some growers continue to cultivate the plant, including for fruit presented to the Imperial Household, Ōmi Shrine, which enshrines Emperor Tenji, and Yasukuni Shrine.
The stems and roots are also used in the Japanese crude drug known as yamokka (野木瓜), traditionally used as a diuretic.
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