The genus Setaria (formerly called bristle grass) includes nearly 125 species of annual and perennial grasses, mostly of tropical Africa but found in warm areas of all the continents. The plants are taller than those of Alopecurus, with bristly flower clusters and flat, thin leaf blades. More than 40 species are found in North America. A few are forage grasses, as plains foxtail (S. macrostachya). Foxtail millet (S. italica; see millet) is the only economically valuable species. Yellow foxtail (S. lutescens or S. glauca) and green foxtail (S. viridis), named for the colour of their bristles, are common in cornfields and disturbed areas. Bristly foxtail (S. verticillata), whose barbed bristles stick to animals and clothing, is also found in those places; the flower clusters from different plants may stick together, forming dense tangles. The name giant foxtail is applied to two weedy annuals: S. faberi and S. magna.