A large family; shrubs, or small trees, of temperate and warm regions, some with bitter, astringent properties, often thorny; leaves mostly alternate; stipules minute; flowers often in showy clusters, small, regular; calyx-lobes and stamens four or five; petals usually four or five, sometimes lacking, with claws. The short calyx-tube is lined with a fleshy disk and on this are borne the petals and the stamens, alternate with the sepals and opposite the petals, with swinging anthers. In some cases, some of the flowers have only pistils or only stamens. The ovary superior or partly inferior; the fruit a berry or capsule.

There are many kinds of Ceanothus, largely western; flowers small, blue or white, in clusters; calyx bell-shaped, five-lobed, with a colored, petal-like border; petals five, the tips arching to form a tiny hood, with long claws; stamens five, long, protruding, with threadlike filaments; ovary partly inferior; style three-cleft; capsule splitting open elasticaliy so as to scatter the three, hard nutlets, The flowers make a soapy lather when rubbed in water, hence the name Soap-bush, and the kinds with rigid branches are called Buckbrush. Red-root is another name. Mountain Lilac is the commonest name, but misleading. Lilacs belong to another family.