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Rhus

Family

Anacardiaceae

Common names

Sumach

A large genus of shrubs, small trees, or climbers, with ternate or pinnate leaves, found in most temperate regions of the globe, and occasionally in the tropics. About a dozen species are grown in the open air in the British Isles, but several others (such as R. succedanea) can be cultivated in Corn­wall and similar places. Individually the flowers of the sumachs are small and of little beauty, being greenish, yellowish, or dull white, but in a few species the panicles are sufficiently large and the flowers white enough to give a pleasing effect. In some species the fruits are handsome, but, on the whole, their value in gardens is in the size and autumn colouring of the foliage. The leading characters of the genus are the alternate leaves and usually dioecious flowers, the five-lobed calyx (which adheres to the fruit), the five petals, the one-celled ovary with three styles, and the usually globose fruit, either glabrous or hairy, containing one bony seed.

The juice of several species, notably R. radicans and R. vernix, is exceedingly acrid and poisonous to many people, but care should be taken in pruning or making cuttings of any of the species. R. vertticiflua yields the famous lacquer of Japan. The leaves of several species have also an economic value either for dyeing or tanning, and the fruits of some, such as R. succedanea and R. verniciflua, give a wax used for candle-making.

The cultivation of all the sumachs is simple. They do not require a very rich soil except when they are grown purely for size of foliage as R. tjphina (q.v.) and R. glabra sometimes are. Where autumn colour is desired, ordinary garden soil without added manure is sufficient. Like many other trees with soft wood and a large pith, they are subject to the attacks of the ‘coral-spot’ fungus (Nectria cinnabarina). Branches so attacked should be cleanly cut off and burnt, the wound coated with tar. Most can be propagated by root-cuttings, and seed is often available.

Species articles