Vegetation Topography, altitude, water supply, and soil determine the character of the and Fauna vegetation. Approximately 11 per cent of Iran is forested, most extensively in the Caspian region. Thorny shrubs and fern also abound. Willow, poplar and plane trees grow in the ravines, as do many species of creepers. Desert sand dunes, which hold water, support thickets for brush.
Forests flow the courses of surface or subterranean waters.
Oases support tamarisk, poplar, date palm, myrtle, oleander, acacia, willow, elm, plum, mulberry trees, and vines. In swamp areas, reeds and grass provide good pasture. City Average Max. National Meterology Organization Iran has long been famous for its fruit, and Iran's old language, Farsi, has provided the European languages with their words for lemon, orange and peach. The Caspian region produces citrus fruit, while dates and bananas grow along the Persian Gulf.