(L.) Millsp., Publ. Field Colombian Mus., Bot. Ser. 2:412. 1916
Monoecious annual herb, commonly with a thick prostrate root, usually forming dense mats; stems usually villous above and glabrous below, often reddish-brown; sap ± milky. Leaves opposite, simple; stipules distinct, linear, toothed; blades oblong-elliptic, rounded to acute at apex, rounded to subcordate and inequilateral at base, 4-10 mm long, 2-5 mm wide, glabrous above, glabrous to sparsely pubescent below, inconspicuously serrate. Flowers naked, the cyathia 1 to several in axils of lateral branches, the glomerules less than 4 mm wide; disk with glands broadly elliptic to rounded, reddish; stamen 1; styles 3, bifid. Capsules long-ovoid, appressed-pubescent, to 1.3 mm long, not fully exserted but splitting cyathium at maturity; seeds conical-ovoid, to 1 mm long, 4-angled, tan. Croat 16527.
Collected once on the mossy sides of a concrete drainage ditch near the laboratory. Flowers and fruits throughout the year, especially during the rainy season.
Throughout the tropics of the New World. In Panama, known throughout from tropical moist forest, as well as from tropical dry forest in Coclé, from premontane moist forest in the Canal Zone, and from tropical wet forest in Colon.