Stems prostrate to decumbent-ascending, 0.2-1.5(-2) dm, herbage glabrous to sparingly farinose. Leaves: blade of principal leaves oblanceolate to spatulate, 0.4-2.2 cm × 1-4(-6) mm, attenuate into petiolar base, margins entire, apex obtuse to rounded. Flowers: outer pistillate, usually lacking perianth; central bisexual, perianth segments 2-3, spatulate or obovate, ca. 0.5 mm; stamens 1-2 . Utricles 0.5-0.7 mm; pericarp readily separating from seed, pale brown, turning black and dull, tuberculate-papillose. Seeds brown, ± lenticular, shiny. 2n = 18.

Flowering late spring-summer. Moist, subalkaline streambanks and meadows; 100-2600 m; Calif., Nev., Oreg.; Mexico (Baja California).