steppe (stĕp) [key], temperate grassland of Eurasia, consisting of level, generally treeless plains. It extends over the lower regions of the Danube and in a broad belt over S and SE European and Central Asian Russia, stretching E to the Altai and S to the Transbaykal and Manchurian plains. The term is sometimes applied to the corresponding temperate grasslands of Hungary (Puszta), the prairies of the United States, the pampas of South America, and the highveld (see veld) of South Africa; it is sometimes also applied to the semiarid regions on the fringe of the hot deserts. The steppe consists of three vegetation zones with significant differences in climate—the wooded, or forest, steppe; the tillable steppe, or prairie; and the nontillable steppe. The wooded steppe has deciduous trees and the heaviest annual rainfall, over 16 in. (41 cm). The tillable steppe has black earth and an annual rainfall of between 10 and 15 in. (25–38 cm). The nontillable steppe is a semidesert, found especially around the Caspian Sea, with an annual rainfall of less than 10 in. (25 cm). There is some grazing, and its soils are relatively fertile under irrigation. Although the tillable steppe was originally grassland used almost exclusively for grazing, it is now almost entirely under cultivation. Some of the world's most productive agricultural areas, such as Ukraine and the U.S. wheat belt, are situated on the tillable steppe.