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Juglans ailantifolia Carr.

Japanese Walnut

Modern name

Juglans ailantifolia Carrière


J. sieboldiana Maxim., not Goeppert

A tree over 50 ft high, with stout young shoots clothed, like the common stalk of the leaf, with glandular hairs. Leaves 112 to 2 (occasionally 3) ft long, composed of eleven to seventeen leaflets, which are oblong, taper-pointed, finely toothed, obliquely rounded or slightly heart-shaped at the base, 3 to 7 in. long, 112 to 2 in. wide, downy on both surfaces, especially beneath. Male catkins slender, up to 1 ft long. Fruits clustered on long racemes, roundish ovoid, 2 in. long, covered with sticky down; nut about 114 in. long, rounded at the base, pointed at the top, nearly glabrous, but with a prominent ridge at the union of the two halves.

Native of Japan and Sakhalin; introduced to Europe about 1860, by Siebold. It is abundant in the forests of Japan, and its nuts are valued as food there. In Britain it gives no promise of bearing fruit to any advantage, and in spite of the considerable period that has elapsed since its introduction, there are few large specimens in the country. It appears to differ from J. mandshurica chiefly in the apex of the leaflet being more abruptly tapered and shorter-pointed, and in the prominent ridge and smoother surface of the nut.

The best specimen of the Japanese walnut so far recorded in Britain grows in the Edinburgh Botanic Garden; pl. 1906, it measures 55 × 6 ft (1967). There are three examples at Batsford Park, Glos., planted by the first Lord Redesdale. The two largest are both 45 ft high with girths of 614 ft at 3 ft and 7 ft at 4 ft respectively (1963). Other examples recorded are: East Bergholt Place, Suffolk, 30 × 414 ft (1966); West Hill Nurseries, Winchester, 35 × 3 34 ft (1961); Glasnevin Botanic Garden, Dublin, Eire, 37 × 314 ft (1966).

var. cordiformis (Maxim.)Rehd. J. cordiformis Maxim. – Nuts thin-shelled, with a broad, heart-shaped base. This is not known in the wild. An example at Kew, pl. 1899, measures 47 × 312 ft (1956). It flowers freely and the male inflorescences are very striking, being almost yellowish green. The fruits occasionally mature. There is another of 40 × 4 ft in the Edinburgh Botanic Garden (1967).

From the Supplement (Vol. V)

specimens: Petworth House, Sussex, 52 × 4 ft (1983); Batsford Park, Glos., 46 × 814 ft at 2 ft, 46 × 734 ft and 42 × 812 ft (1980); East Bergholt Place, Suffolk, 48 × 434 ft (1972); and of var. cordiformis, Althorp, Northants, 44 × 412 ft (1983); Edinburgh Botanic Garden, 40 × 414 ft (1981).



Other species in the genus