Plants annual; roots fibrous. Stems prostrate to suberect; trichomes conspicuous at nodes and in inflorescence; branches to 30 cm. Leaf blades linear to lanceolate, terete to hemispheric, 5-30 × 1-5 mm, apex acute or subacute; involucrelike leaves 8-9(-14). Flowers 25-55 mm diam.; petals pink, red, purple, yellow, bronze, or white, obovate, 15-25 × 15-20 mm; stamens 40 or more; stigmas 5-8. Capsules ovoid, (3.5-)4-6.5 mm diam. Seeds steely gray, often iridescent, orbiculate or elongate, flattened, 0.75-1 mm diam.; surface cells obscurely stellate with tubercles mostly abaxially. 2n = 18. Flowering late spring-fall. Sandy soils; 0-2000 m; introduced; Ont.; Ala., Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Md., Mass., Mich., Minn., Miss., Mo., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Pa., R.I., S.C., S.Dak., Tenn., Tex., Vt., Va., W.Va., Wis.; South America; naturalized in Europe. Portulaca grandiflora is naturalized in gardens and has escaped to roadsides and waste places. Studies of seed surfaces from specimens representing 100 years of collections with distribution over the United States show remarkable consistency in seed morphology. Tubercles may extend onto the lateral surface, where they are widely scattered. Only one specimen was found with no tubercles at all.
Stems diffusely branched, ascending or widely spreading, 2-4 dm, hairy at the nodes; lvs linear, subterete, 1-3 cm, the cauline alternate, the terminal crowded, forming an involucre intermingled with long hairs; fls white or various brilliant shades of red or yellow, 2-4 cm wide; stamens numerous, ca 40 or more; style-branches 5-9; 2n=18, 36. Native of Argentina, occasionally escaped from cult. All summer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.