Classification of root systems of forbs of grassland and a consideration of their significance

Plants other than grasses constitute an impor-tant part of the native grasslands of North Amer-ica. M\4ost of these are forbs, a few are shrubs and half-shrubs. Probably 85 to 90 percent of the forbs are perennial and most are as deeply rooted and many far more deeply rooted than the grasses. Their number varies considerably from place to place. In the prairie of the central part of the North American Lowland and on the hard lands and sandy soils of the Great Plains they compose, perhaps, between 5 and 15 percent of the vegetation. They are least abundant in the drier habitats. A recent summary of the community root habits of grasses and an interpretation of the finding