''Juglans ailantifolia'' (synonyms ''J. cordiformis'' and ''J. sieboldiana'' and '' J. mandshurica'' var. ''sachalinensis''), the Japanese walnut ( ja, 鬼胡桃 ''oni-gurumi''), is a species of

walnut A walnut is the edible seed of a drupe of any tree of the genus ''Juglans'' (family Juglandaceae), particularly the Persian or English walnut, '' Juglans regia''. Although culinarily considered a "nut" and used as such, it is not a true ...

native to Japan and

Sakhalin Sakhalin ( rus, Сахали́н, r=Sakhalín, p=səxɐˈlʲin; ja, 樺太 ''Karafuto''; zh, c=, p=Kùyèdǎo, s=库页岛, t=庫頁島; Manchu: ᠰᠠᡥᠠᠯᡳᠶᠠᠨ, ''Sahaliyan''; Orok: Бугата на̄, ''Bugata nā''; Nivkh ...

. It is a

deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, ...

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

growing to tall, rarely , and 40–80 cm stem diameter, with light grey bark. The leaves are pinnate, 50–90 cm long, with 11-17 leaflets, each leaflet 7–16 cm long and 3–5 cm broad. The whole leaf is downy-pubescent, and a somewhat brighter, yellower green than many other tree leaves. The male

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

s are inconspicuous yellow-green catkins produced in spring at the same time as the new leaves appear. The female flowers have pink/ red pistils. The

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...

is a

nut Nut often refers to: * Nut (fruit), fruit composed of a hard shell and a seed, or a collective noun for dry and edible fruits or seeds * Nut (hardware), fastener used with a bolt Nut or Nuts may also refer to: Arts, entertainment, and media Co ...

, produced in bunches of 4-10 together; the nut is spherical, 3–5 cm long and broad, surrounded by a green husk before maturity in mid autumn.

Uses

The edible nuts have an oily texture. The husks are also used to make a yellowish dye. The very bold, decorative leaves and the attractive catkins produced in spring make it an excellent ornamental tree for planting in parks and large

garden A garden is a planned space, usually outdoors, set aside for the cultivation, display, and enjoyment of plants and other forms of nature. The single feature identifying even the wildest wild garden is ''control''. The garden can incorporate bot ...

s. File:P4260728.jpg, Heartnut in flower Naturalis Biodiversity Center - L.3711472 - Juglans ailantifolia Carrière var. cordiformis (Makino) Rehder - herbarium sheet.jpg, Herbarium sheet, 19th century Unlike the closely related and very similar North American butternut, Japanese walnut is resistant to the canker

disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...

caused by the

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from t ...

Sirococcus clavigignenti-juglandacearum ''Ophiognomonia clavigignenti-juglandacearum'' is a mitosporic fungus that causes the lethal disease of butternut trees (''Juglans cinerea''), butternut canker. It is also known to parasitize other members of the genus ''Juglans'' on occasion, ...

''. This has led to its being planted as a replacement for butternuts in North America. The two species hybridise readily; the resulting hybrid ''Juglans x bixbyi'' (otherwise known as ''J. cinerea x ailantifolia'' or 'buartnut') is also resistant to canker and is likewise planted as a replacement for butternuts. Japanese walnut is distinguished from butternut by its larger leaves and round (not oval) nuts.
Prospect Rock Permaculture
in Vermont has been backcrossing buartnuts with native butternuts, resulting in 'butterbuarts', which will most likely bear greater resemblance to the butternut parentage, although may also be more susceptible to the canker. The

wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin ...

is light and takes polish well, but is of much lower quality than

Persian walnut ''Juglans regia'', the Persian walnut, English walnut, Carpathian walnut, Madeira walnut, or especially in Great Britain, common walnut, is an Old World walnut tree species native to the region stretching from the Balkans eastward to the Himala ...

wood. It is often used to make furniture.

Cultivars

The heartnut is a

cultivar A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture ...

of Japanese walnut distinguished by its fruit, which is heart-shaped in cross-section, very hard to crack, and able to yield unbroken nut meat when cracked. The heartnut is a sweet nut without a bitter aftertaste often intrinsic with black and Persian walnuts. This is the subspecies that hybridizes with butternuts, creating 'buartnuts', or ''Juglans x bixbyi''. Toyo Tire evaluated that the shell was very hard and that the fragments were sharp, and it came to be used as a material for snow tires (studless tires).

Diseases

The only significant disease Japanese walnuts are susceptible to is the Walnut Bunch Disease.

External links

* * {{Taxonbar, from=Q1655870 ailantifolia Flora of Japan Flora of Sakhalin Japanese fruit