Backyard Horticulture The genus Digitaria, a member of the grass family, contains many species of crabgrass all over the world. But according to Texas A&M University, “Two species of crabgrass are found throughout the semi-tropical and temperate zones of the U.S. - smooth crabgrass (Digitaria ischaemum) and hairy crabgrass (Digitaria sanguinalis).