A rather large family, mostly of the Mediterranean region; herbs or low shrubs; flowers regular, perfect, all the parts borne on the receptacle; sepals five, the two outer ones smaller and bract-like, or lacking; petals three to five; stamens many; ovary superior, one-celled, with a single style, or none; fruit a capsule, with several or many seeds.

There are many kinds of Helianthemum, widely distributed, perennials; leaves alternate, undivided, toothless; flowers yellow and, in most North American species, of two sorts; the earlier ones with large, yellow petals, very numerous stamens and a many-seeded pod; the later ones, small, clustered, with small petals or none, three to ten stamens, and small, few-seeded pods.