Stems slender, branching from near base, up to 25 cm. long, creeping and rooting in lower part, ascending in upper part, purplish. Branchlets ± bifariously pubescent, sts evenly so. Lvs opp., rather distant, on slender petioles up to ± 4 mm. long; lamina (6)-10-15-(20) × 4-10 mm., ovate to ovate-oblong, subcoriac., glab.; margins obscurely to distinctly denticulate to entire or sinuate. Fls few, near or remote from upper part of branchlets, (6)-9-12 mm. or more diam. Calyx deeply cleft; lobes lanceolate, acute, glab., about 1/2 length petals; petals white, bifid. Capsules (20)-40-50 mm. long, glab.; peduncles 5-10-(15) cm. long. Seeds smooth, testa minutely reticulate.

2n = 36

n = 18

Creeping herb forming thick loose mats, either in very wet ground or floating. Stems 2-20 cm long, creeping and rooting below, with short bristly hairs all round. Lamina of lf elliptic to narrowly-ovate, 6-15 × 3-8 mm. Floral tube 1.3-2 mm deep, glabrous or somewhat hairy. Petals usually white, very rarely pink at first, but flushed pink after pollination, 6.5-12 × 4-8 mm. Capsule glabrous, (3)-4-6.5 cm long; fruiting pedicel (1)-2.5-12 cm long.