A Biological community that contains few trees or shrubs, is characterized by mixed herbaceous (nonwoody) vegetation cover, and is dominated by grasses or grasslike plants. Grassland ecosystems range from the dense bamboo of the Amazonian tropics to the cool northern steppes of Russia, and from dry plains in the western United States to Canadian arctic grasslands. Mixtures of trees and grasslands occur as savannas at transition zones with forests, as in the east-central United States, or where rainfall is marginal for trees, such as in south-central Africa and Australia. About 1.2 × 10⁸ mi² (4.6 × 10⁷ km²) of the Earth's surface is covered with grasslands, which make up about 32% of the plant cover of the world. The proportion of original grasslands varies widely among continents with about 44% remaining in Europe and less than 10% in Australia, although the latter has vast expanses of savannas. In North America, grasslands include the Great Plains, which extend from southern Texas into Canada. The European meadows cross the subcontinent, and the Eurasian steppe ranges from Hungary eastward through Russia to Mongolia; the pampas cover much of the interior of Argentina and Uruguay. Vast and varied savannas and velds can be found in central and southern Africa and throughout much of Australia.