Big bluestem (A. gerardii), often more than 2 metres (6 ¹/₂ feet) tall, is the characteristic plant species of the North American tall-grass prairie. It is sometimes known as turkeyfoot, in reference to its forked flower cluster. Little bluestem (A. scoparius), 0.5 to 1.5 m tall, is found in drier prairie areas. Both species are good hay and pasture plants. Sand bluestem (A. hallii), with yellowish spikelets, grows on sand hills in the central and western United States. Broom sedge (A. virginicus) and bushy beard grass (A. glomeratus) are coarse grasses, unsuitable for forage, that grow in poor soils in eastern and southern North America. Silver beard grass (A. saccharoides), 0.6 to 1.3 m tall, has silvery white flower clusters 7 to 15 centimetres long; it is a forage grass in the southwestern United States.