Damiana branches have a reddish-brown bark, and when young, are covered with white and cottony hairs. The leaves are about 2 cm long, obovate, tapering at the base to a short, slender leafstalk. When young the leaves are slightly pubescent yet become smooth when old. They are pinnately veined, and the margin is toothed with 8 to 10 teeth. The flowers are small, yellow and subsessile near the end of the short branches. The calyx is tubular, hairy externally, colored like the petals, and 5-toothed at the apex. There are five yellow petals inserted on the tube of the calyx. The fruit are 1-celled, globular, rough, and contain from 3 to 6 kidney-shaped seeds. Although T. diffusa is considered official it is likely that commercial preparations may contain allied species, such as Turnera ulmifolia.