Pentas

Perennial herbs or subshrubs; stems erect or straggling from a fibrous or woody rootstock. Leaves paired or whorled, usually lanceolate, elliptic or linear; stipules multipartite, segments colleter-tipped. Flowers mono-, di- or trimorphic; usually in dense, complex cymes. Calyx 5-lobed; lobes equal or unequal, some accrescent in fruit; tube campanulate-turbinate. Corolla 5-lobed, white; lobes equal or somewhat unequal; tube cylindric or +/- funnel-shaped, sometimes campanulate above, bearded in throat. Stamens 5; in monomorphic flowers enclosed in an abrupt apical dilation of tube and style exserted; in dimorphic flowers tube gradually dilated at apex in short-styled flowers, and abruptly dilated in long-styled flowers. Disc present, sometimes becoming obconic. Ovary 2-locular, with many ovules in each locule attached to semiglobose placentas on septum; style filiform; stigma of 2 glandular, terete lobes, or thickened and terete. Fruit a 2-valved, ribbed, beaked capsule, opening at apex into 4 valves; sometimes separating into 2 cocci. Seeds usually subglobose, often 3-winged, reticulate or honeycombed. x = 10 (9) (polyploidy).