Annual herb; stems prostrate, much-branched, to ca. 14 cm long, weak and filiform, 0.5 mm wide, glabrous, creeping and rooting at nodes, forming rooting mats, with nodal tufts of to 2 mm long hairs. Leaves opposite; blade flat, obovate, elliptical, lanceolate or ovate, 2-12 x 1-6 mm (typically 4 x 2 mm in the Guianas), obtuse or acute at apex. Inflorescence of 1-2(-3)terminal flowers, surrounded by long white hairs and an involucre of 4-5triangular, obtuse, membranaceous, 2-3 mm long leaves; flowers pedicellate. Sepals subequal, triangular-oblong, 2-3.5 x 2 mm, apex obtuse-rounded; petals yellow, elliptical or ovate, 3-6 mm long; stamens 7-12, filaments pilose, anthers more or less suborbicular; ovary conical-ovoid, style 2.5-3.5 mm long, 3- to 4-branched, stigmas ca. 0.5 mm long. Fruit ovoid, to 6 x 0.5 mm, circumscissile in lower third, operculum tubular-campanulate, 1.5-2.5 mm wide; seeds bluish-grey, 0.8-1.0 mm wide, densely granular- or spiny-tuberculate.