Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Genus Description - Sep 2, caducous; pet 5 (rarely more), distinct, fugacious; stamens 4–45, distinct; filaments slender; ovary ovoid; styles partly or wholly united; capsule 1-celled, many-seeded; seeds cochleate, flattened, minutely roughened; glabrous, succulent, annual or perennial herbs with conspicuous fls in long-peduncled bracteate cymes. Our spp. have a short taproot that in age becomes multicipital, producing from each crown a short stem that has numerous crowded, succulent, terete lvs 3–8 cm, and is prolonged above into a slender scape cymosely branched above and bracteate at the nodes; bracts triangular, 2–5 mm, prolonged backward at base; fls pinkish to deep rosy-red, open for only a few hours in full sunshine; midveins of the capsule-valves often persistent, as well as the placentas; seeds gray over black, 1 mm wide, minutely roughened. 30+, mostly warm N. Amer.