| Japanese walnut | |
|---|---|
 | |
| Foliage and nuts | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Rosids |
| Order: | Fagales |
| Family: | Juglandaceae |
| Genus: | Juglans |
| Section: | Juglans sect.Cardiocaryon |
| Species: | J. ailantifolia |
| Binomial name | |
| Juglans ailantifolia | |
Juglans ailantifolia (synonymsJ. cordiformis andJ. sieboldiana andJ. mandshurica var.sachalinensis), theJapanese walnut (Japanese:鬼胡桃,romanized: oni-gurumi), is a species ofwalnut native toJapan andSakhalin.[1]
It is adeciduoustree growing to 20 m (66 ft) tall, rarely 30 m (98 ft), and 40–80 centimetres (16–31 in) stem diameter, with light grey bark. Theleaves are pinnate, 50–90 cm (20–35 in) long, with 11–17 leaflets, each leaflet 7–16 cm (3–6+1⁄2 in) long and 3–5 cm (1–2 in) broad. The whole leaf is downy-pubescent, and a somewhat brighter, yellower green than many other tree leaves.
The male flowers are inconspicuous yellow-greencatkins produced in spring at the same time as the new leaves appear. The female flowers have pink/red pistils. The fruit is anut, 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.
The only significant disease Japanese walnuts are susceptible to is thewalnut bunch disease.
Theheartnut is acultivar 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', orJuglans x bixbyi.
The edible nuts have an oily texture. The husks are also used to make a yellowish dye.
The very bold, decorative leaves and catkins produced in spring make it a commonornamental tree for planting in parks and large gardens.
Unlike the closely related and very similar North Americanbutternut, Japanese walnut is resistant to thecanker disease caused by thefungusSirococcus clavigignenti-juglandacearum.[2] This has led to its being planted as a replacement for butternuts in North America. The two specieshybridise readily; the resulting hybridJuglans x bixbyi (otherwise known asJ. 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 thanPersian walnut wood. It is often used to make furniture.
Toyo Tire evaluated the shell of heartnut as being very hard and the fragments sharp, and it came to be used as a material for snow tires (studless tires).[citation needed]
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Media related toJuglans ailantifolia at Wikimedia Commons