Juglans ailantifolia

Classification System: APG IV

Superregnum: Eukaryota
Regnum: Plantae
Cladus: Angiosperms
Cladus: Eudicots
Cladus: Core eudicots
Cladus: Rosids
Cladus: Eurosids I
Ordo: Fagales

Familia: Juglandaceae
Subfamilia: Juglandoideae
Genus: Juglans
Species: Juglans ailantifolia
Name

Juglans ailantifolia Carrière, Rev. Hort. (Paris) 50: 414, fig. 85–86 (1878).
Synonyms

Heterotypic
Juglans allardiana Dode, Bull. Soc. Dendrol. France 11: 34 (1909).
Juglans coarctata Dode, Bull. Soc. Dendrol. France 11: 36 (1909).
Juglans japonica Hort. ex Lavallée, Arbor. Segrez. 1 (1880)
Juglans japonica Siebold ex Miq., Ann. Mus. Bot. Lugduno-Batavi 3: 103 (1867).
Juglans lavallei Dode, Bull. Soc. Dendrol. France 11: 37 (1909).
Juglans macrophylla Carrière, Rev. Hortic. 415 (1878)
Juglans mandshurica Miq., Ann. Mus. Bot. Lugd. Bat. 3: 104 (1867)
Juglans mirabunda Koidz., Acta Phytotax. Geobot. 6: 17 (1937).
Juglans nigra Thunb., Fl. Jap. 195 (1784)
Juglans sachalinensis Komatsu, Icon. Pl. Koisikav. 2: 111 (1915).
Juglans mandshurica var. sachalinensis (Komatsu) Kitam., Acta Phytotax. Geobot. 14: 14 (1949).
Juglans subcordiformis Dode, Bull. Soc. Dendrol. France 11: 43 (1909).
Juglans coreensis Siebold, Verh. Batav. Genootsch. Kunsten 12: 27 (1830).
Juglans kurumi Siebold, Verh. Batav. Genootsch. Kunsten 12: 27 (1830).
Juglans sieboldiana Maxim., Bull. Acad. Imp. Sci. Saint-Pétersbourg, sér. 3, 18: 60 (1872).
Juglans mandshurica var. sieboldiana Makino, New Illustr. Fl. Japan: 81 (1961).
Juglans mandshurica f. sieboldiana (Makino) Kitam., Acta Phytotax. Geobot. 14: 14 (1949).

Distribution
Native distribution areas:

Continental: Asia-Temperate
Regional: Russian Far East
Kuril Islands, Sakhalin.

References: Brummitt, R.K. 2001. TDWG – World Geographical Scheme for Recording Plant Distributions, 2nd Edition
References
Primary references

Carrière, É.-A. 1878. Juglans ailantifolia. Revue Horticole (Paris) 50: 414–415, fig. 86. BHL Reference page.

Additional references

Ohwi, J. 1965. Flora of Japan (translated by F.G. Meyer & E.M. Walker). 1067 pp. Smithsonian Institution, Washington, D.C. BHL Reference page.

Links

Govaerts, R. et al. 2022. Juglans ailantifolia in Kew Science Plants of the World online. The Board of Trustees of the Royal Botanic Gardens, Kew. Published online. Accessed: 2022 Mar 02. Reference page.
Hassler, M. 2022. Juglans ailantifolia. World Plants: Synonymic Checklists of the Vascular Plants of the World In: Roskovh, Y., Abucay, L., Orrell, T., Nicolson, D., Bailly, N., Kirk, P., Bourgoin, T., DeWalt, R.E., Decock, W., De Wever, A., Nieukerken, E. van, Zarucchi, J. & Penev, L., eds. 2022. Species 2000 & ITIS Catalogue of Life. Published online. Accessed: 2022 Mar 02. Reference page.
Tropicos.org 2022. Juglans ailantifolia. Missouri Botanical Garden. Published online. Accessed: 02 Mar 2022.
International Plant Names Index. 2022. Mar 02. Published online. Accessed: 2022.

Vernacular names
čeština: Ořešák japonský
Deutsch: Japanische Walnuss
English: Japanese Walnut
suomi: Japaninjalopähkinä
français: Noyer du Japon
Türkçe: Japon cevizi

Juglans ailantifolia (synonyms J. cordiformis and J. sieboldiana and J. mandshurica var. sachalinensis), the Japanese walnut (Japanese: 鬼胡桃 oni-gurumi), is a species of walnut native to Japan and Sakhalin. It is a deciduous tree growing to 20 m (66 ft) tall, rarely 30 m (98 ft), 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 flowers 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 is a nut, 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 gardens.

Heartnut in flower

Herbarium sheet, 19th century

Unlike the closely related and very similar North American butternut, Japanese walnut is resistant to the canker disease caused by the fungus Sirococcus clavigignenti-juglandacearum. 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 is light and takes polish well, but is of much lower quality than Persian walnut wood. It is often used to make furniture.
Cultivars

The heartnut is a cultivar 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.