Herbs, perennial. Stems procumbent [suberect], with fine stellate pubescence and long simple hairs, not viscid. Leaves alternate and distichous; stipules persistent, inconspicuous, subulate; blade ovate-oblong [lanceolate-ovate], unlobed, base cordate, margins crenate-dentate, surfaces tomentose. Inflorescences axillary, solitary flowers [fasciculate]; involucel absent. Flowers: calyx accrescent, inflated in fruit, brownish-membranous at maturity, completely enclosing fruit, lobes unribbed, ovate, stellate-hairy; corolla white or rose; staminal column included; ovary 5[–9]-carpellate; style 5[–9]-branched; stigmas capitate. Fruits schizocarps, erect, not inflated, subglobose, not indurate, fragile-walled, glabrous; mericarps 5, 1-celled, without dorsal spurs, indehiscent. Seeds 1 per mericarp, glabrous. x = 8.
Introduced; Tex., n Mexico, South America (Argentina, Bolivia, Brazil, Paraguay, Peru, Uruguay).
Species 4 (1 in the flora).