This section is from the book "Commercial Gardening Vol4", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
There are some 120 species in this genus, mostly shrubs or low trees, with graceful foliage, many with resinous, caustic, or even poisonous juice. R. cotinoides (fig. 433), the "Chittam Wood", grows 20-35 ft. high in the United States. Its undivided leaves assume brilliant shades of scarlet and crimson suffused with yellow and orange in autumn.
Fig. 433. - Rhus cotinoides.
The South European R. Cotinus, the Smoke Tree, Wig Tree, or Venetian Sumach, is somewhat similar, but is much more common. It has roundish leaves, and is remarkable for the cloudy masses of feathery flower stalks in autumn. There is a drooping variety, pendula, and a deep-purple -coloured one, atropurpurea. R. glabra has long pinnate leaves, which become red or scarlet in autumn. The variety laciniata has deeply cut leaflets. R. Osbecki, also with pinnate leaves, has the midrib winged on each side. The North American Stag's-horn Sumach (R. typhina) grows up to 30 ft. high, and has hairy pinnate leaves, the rachis and main veins of the leaflets being covered with velvety-brown hairs. There are other species, like Michauxi, succedanea (rather tender), and vernicifera, the Japanese Lacquer or Varnish Tree; and to them must be added the poisonous North American species (R. Toxicodendron and R. venenata), the foliage of which is ornamental but dangerous.