Herbs, annual (perennial in P. suffrutescens). Roots tuberous, fleshy, fibrous, or small taproots. Stems erect to prostrate, branched, fleshy or suffrutescent; trichomes in inflorescence or stem nodes absent or present, glabrous otherwise. Leaves alternate or subopposite, congested and involucrelike immediately proximal to inflorescence; blade terete, subterete, or flattened. Inflorescences terminal in clusters, or axillary on short branches. Flowers sessile or subsessile, usually open only in sunshine; sepals broadly clasping at base, herbaceous to scarious, falling from top of capsule; petals ephemeral, 5-7, usually distinct, margins usually entire; stamens (4-)6-40(-100); ovary half inferior to inferior, plurilocular proximally to 1-locular distally, placentation free-central; style 1, short, stigmas 3-8(-18). Capsules membranaceous, chartaceous, dehiscence circumscissile. Seeds many, brown to black or gray, reniform to cochleate; seed coat smooth or variously sculptured, granular to stellate-tuberculate or spiny. x = 4, 5, 8, 9.
Species 100-125 (10 in the flora): nearly worldwide, primarily tropical and subtropical, also temperate.
SELECTED REFERENCES
Legrand, C. D. 1962. Las especies Americanas de Portulaca. Anales Mus. Hist. Nat. Montevideo, ser. 2, 7: 1-147. Matthews, J. F. and P. A. Levins. 1985. The genus Portulaca in the southeastern United States. Castanea 50: 96-104. Walters, S. M. 1964. Portulaca. In: T. G. Tutin et al., eds. 1964-1980. Flora Europaea. 5 vols. Cambridge. Vol. 1, p. 114. Wilson, P. 1932b. Portulaca. In: N. L. Britton et al., eds. 1905+. North American Flora.... 47+ vols. New York. Vol. 21, pp 328-336.
