The rukam, also called rukam manis, rukam gajah and Indian prune in Malaya; khrop dong in Thailand, is a much-branched, crooked tree to 40 or even 65 ft (12-20 m)-our tree at the Canary Islands is growing very slowly-, sometimes thornless in cultivation but usually heavily armed with forked, woody spines on the trunk and old branches. The leaves are evergreen, spiralled, red when young, elliptic-oblong, 3 to 6 in (7.5-15 cm) long, 1 1/4 to 2 1/2 in (3.2 -6.25 cm) wide, coarsely toothed, slightly shiny.
Flowers grow in small clusters in the leaf axils. Male and female are usually on separate trees; occasionally both occur on the same plant. We on Gomera have one tree with male and female flowers.There are no petals; the male have many stamens.
Fruits, borne on old branches or on the trunk, are nearly round, slightly flattened at the apex,1/2 to 1 in (1.25-2.5 cm) wide, dark purple-red, smooth, with whitish, juicy, acid flesh. There are 4 to 7 flat seeds.
The tree is native to India, Southeast Asia, Malaysia and Oceania; cultivated in southern Malaya and Indonesia. It is adapted to elevations up to 5,200 ft (1,600 m). A few specimens have been grown in Florida. The fruits are eaten raw, especially after rolling them between the palms to reduce astringency-we here at the Canary Islands eat them as the come, a slight astrigency is welcome-. They are also cooked, made into pie, jam and chutney. The young shoots are marketed and eaten raw in Java.
Analyses made in the Philippines show:
Calories 83 per 100 g; moisture 77 %; protein 1.7 % fat
1.26 % ; reducing sugars 4.3 % ; fiber, 3.7 % ; other
carbohydrates 11 % ;ash 0.8 %; acidity, 1.3 %.