It is widespread throughout much of the U.S, but relatively uncommon in California. Knotroot foxtail is usually not considered a weed in natural habitats. It typically inhabits open dry or wetland sites, grasslands, and chaparral. However, it is sometimes weedy in agronomic crops, orchards, vineyards, and drainage areas. It spreads primarily by seeds.
African bristlegrass is an uncommon wetland perennial with short rhizomes .
Introduced from tropical Africa as an experimental forage grass.