plants containing tannins in quantities sufficient for industrial use. Tannins are concentrated mainly in the vacuoles of the parenchyma cells of roots and rhizomes (root tannin plants) or those of the bark, leaves, wood, fruits, and galls (in the respective types of plants). Tannins are involved in basic biochemical reactions in the plants. They also protect plants from being eaten by animals and obstruct the growth of parasitic fungi and bacteria in their tissues.
The basic indicators of the quality of tannin plants are their tannin content and their specific action on skin. Tannin plants are classified according to their tannin content; there are high-tannin plants (containing more than 20 percent tannins), average-tannin plants (with 12-20 percent), and low-tannin plants (less than 12 percent). The most important are the high-tannin plants, which include the quebracho, a wood tannin plant from South America; the bark tannin species of acacia from South Asia, Africa, and Australia and the eucalyptus from Australia; and the fruit tannin plants of the genus Caesalpinia from Central America and two species of oak from the Mediterranean region.
A large number of tannin plants grow in the USSR. The most important are oak, chestnut, spruce, larch, some species of willows, smoke tree, sumac, several bindweed species, sorrel, rhubarb, and sea lavender. In addition to tannins, tannin plants also yield medicinal substances (used in the treatment of poisonings, burns, and stomach disorders), dyes, and raw materials for several branches of the food industry.
REFERENCESChernyshev, P. la. Dubil’nye rasteniia nashei strany. Moscow-Leningrad, 1934.
Voprosy izucheniia i ispol’zovaniia dubil’nykh rastenii v SSSR (collection of articles). Moscow-Leningrad, 1963.
V. N. VEKHOV