A large, deciduous, aromatic tree, very nearly glabrous ; young shoots toruentose. Bark grey, characteristically marked by deep, vertical, parallel fissures, ½in. to 2in thick. Wood moderately
brown, with darker streaks, often beautifully mottled. (Gamble.) Leaves imparipinnate, 6-12in., alternate. Leaflets 5-13 or 7-9, odd one the larger, stalked, side ones opposite, sessile ovate-
oblong, 3-8in., pointed, entire. Flowers green, male and female on the same tree, appearing with the leaves. Male flowers numerous, in pendulous, lateral catkins, 2-5in., long, on the previous year's wood above the leaf scars, often two superposed. Perianth narrow, nearly flat, irregularly 5-lobed, combined with the branch, the free tip of which appears on the underside. Stamens 15-20, nearly sessile. Female flowers 1-3, clustered, sessile, on the ends of branches ; the bracts combined in a pubescent, ovoid involucre aduate to the ovary, its narrow mouth obscurely 4-toothed ; perianth of 4 linear lanceolate lobes inserted on the mouth of the involucre, alternate with its teeth. Ovary 1-celled ; ovule 1. Style arms 2, short, broad, recurved, roughly wrinkled. Drupe ovoid, 2in. long, the green, thick, fleshy rind enclosing a woody wrinkled 2-valved nut ; the edible part consisting of the large, corrugated, 4-lobed cotyledons of the single seed. (Collett.)
Uses : — The bark is used as an anthelmintic and detergent ; the leaves are astringent and tonic, in decoction are supposed to be specific in strumous sores, and to be anthelmintic ; the fruit is also believed to have an alterative effect in rheumatism.
The kernels afford by expression about 50 per cent, of a clear sweet oil, largely used in the hills for culinary purposes and illumination. Stewart states that a large proportion of the oil is prepared by simply bruising the kernel between stones. The oil-cake is a good cattle-food. Walnut oil has a yellow or orange-yellow colour with a slight odour oi' linseed and a nutty flavour. Practical experiments show it to be a strong drying oil. Crossley and Le Sueur (1898) testing a sample expressed in India found it to have constants agreeing well with those previously recorded : Specific gravity at 15.5°, 09259 ; acid value, 10.07 ; saponification value, 192.5 ; iodine value, 143.1 ; Reichert Meissl value, 0.00; insoluble fatty acids, 95.44 per cent. (Agricultural Ledger 1911-12, No. 5. p. 166).
