SUMACH or SUMAC, the name given to numerous shrubs and small trees of the botanical genus Rhus (family Anacardia ceae )which comprises about 15o species, natives chiefly of warm regions. They have a milky or resinous juice; simple or com pound leaves; small flowers, with the parts in fours or sixes; and small, dry, one-seeded, often hairy, sometimes highly-coloured fruits, usually in dense clusters.
The name sumach is given also to the commercial preparation of the dried and ground leaves of the Sicilian or tanners' sumach (R. Coriaria) of southern Europe, long used in making leather.
In North America the sumachs are represented by about 15 species. Several have poisonous foliage, as the poison-ivy (q.v.) ; the non-poisonous sumachs include some of the most attractive American shrubs. Among those found in the eastern States and Canada are the handsome staghorn sumach (R. hirta), sometimes 3o ft. high, and the smaller smooth sumach (R. glabra), some times 20 ft. high, both of which in autumn display highly coloured fruit and foliage. The dwarf or mountain sumach (R. copailina)
is a small shrub in the North and a tree 3o ft. high in the South. Its leaves, as also those of the two preceding, were formerly much used in tanning. The aromatic sumach (R. aromatica), 3 ft. to 8 ft. high, with pleasant-scented foliage, occurs in the eastern States; its western counterpart, the skunk-bush (R. trilobata), with ill-scented foliage, is found from Illinois to Oregon and southward. The mahogany sumach (R. integrifolia), the laurel sumach (R. laurina), and the sugar-bush (R. ovata) are elegant shrubs, native to southern California.
The lacquer-tree (R. vernicifera), of Japan, yields Japan lac quer. The wax-tree (R. succedanea), also of Japan, furnishes wax used in candle-making. R. javanica, of eastern Asia, and R. hirta var. dissecta, a North American form, are planted for their ornamental foliage.