Meridiana Linn. f.
Diffuse, annual or perennial, often trailing or ascending, usually glabrous and fleshy herbs. Leaves simple, alternate or opposite, sometimes subopposite; the uppermost crowded to form a sort of involucre below the flowers, flat or terete-semiterete, fleshy; stipules scarious or modified into a bunch of hairs, rarely absent. Inflorescence a terminal fasciculate cyme or flowers solitary ter¬minal, surrounded by a whorl of leaves. Flowers bisexual, actinomorphic, sessile, perigynous, usually 5-merous, showy, variously coloured; bracts entire or modified into hairs. Sepals 2, fused at the base to form a very short tube partly adnate to ovary and the lobes caducous. Petals 4-6, free or united at the base, inserted on rim of calyx tube, marcescent. Stamens 4-many, free or united at the base, inserted on rim of calyx tube and adnate to petals, rarely epipetalous. Carpels usually more than 3, syncarpous; ovary ovoid, half adnate to calyx, semi-inferior; ovules many, campylotropous; style with 3-8 elongated and radiating stigmas. Fruit brittle with thin membranous wall, subglobose to globose or oblong-conical, unilocular capsule, with transverse (circumscissile) dehiscence. Seeds numerous, minute, reniform or lenticular, testa shining, aculeate, tuberculate or somewhat papillate.
About 200 species, chiefly American but also distributed in other tropical and subtropical regions of the world.