Missouri has 17 species of tick trefoils. Species identification is difficult and often depends on close analysis of the seedpods. The plants in this genus vary, with habits ranging from prostrate (lying on the ground) to erect stems. Flowers are usually in terminal racemes; pink, violet, or white; having the characteristic form of pea flowers. Blooming period is July–September, varying depending on species. Leaves are alternate, 3-divided, varying in shape and length of petiole, the lateral (side) leaflets usually on very short stems with the center leaflet on a longer stem. Fruit in distinct papery pods, which break up into 1-seeded segments that are dispersed by animals, including people.
Similar species: Three species that used to be in genus Desmodium are now placed in the genus Hylodesmum; they are different from desmodiums in several details of flower and fruits. For example, their fruits narrow markedly at their base, forming a stalklike shape, and the constrictions between the segments of the fruit are deep and very unsymmetrical. Despite their new genus name, they are still commonly called tick trefoils and sticktights.