Annual, rarely perennial, glabrous or glabrescent herb, 4-15 cm. Stems prostrate, caespitose. Leaves 0.3-1.2 x 0.1-0.3 cm., alternate, more or less petiolate, oblong-oblanceolate, tapering at base, rarely ciliate; stipules ovate, greenish-white, ciliolate. Flowers sessile or almost so, 5-12 in alternate clusters opposite leaves. Calyx about 1.5 mm., mostly glabrous, with short tube and 5 equal lobes; lobes oblong-ovate, obsoletely white-margined, 3-nerved, obtuse or rarely terminating in a short bristle. Petals minute. Stamens 5. Style short or 0, with 2 rather divergent stigmas. Utricle exceeding calyx. Fl. May-July.