Hymenostephium is a genus of flowering plants in the family Asteraceae. It includes herbs and slender shrubs that occur from Mexico through Central America and into South America. Hymenostephium is characterized by the relatively slender habit of the plants, 1-2 seriate involucres, and relatively small heads of flowers. There is variation in the pappus which, in part, has led to some members having been placed formerly in the now empty genus Haplocalymma, or in separate genera now considered as synonymous with Hymenostephium. Molecular phylogenetic data place the genus as sister to Sclerocarpus and in a relatively basal position in the subtribe Helianthinae, the group that includes the common sunflower (Helianthus annuus).