Plants aquatic or terrestrial, annual. Stems erect when stranded, reddish purple in age, somewhat branched, 2-10 cm. Leaf blades oblong to linear, 1-5 mm, apex obtuse. Inflorescences lax; flowers 1 per node. Pedicels 0.5-6(-10) mm. Flowers 4-merous; sepals triangular-ovate to lanceolate, 0.4-1 mm, apex rounded to obtuse; petals lanceolate, 1-1.5 mm. Follicles ascending, 6-14-seeded, obliquely lanceolate; old follicles spreading, flat. Seeds oblong-ellipsoid, 0.3-0.6 × 0.1-0.3 mm, not papillate, shiny, smooth. Flowering spring. Vernal pools, shores of lakes and streams; 0-2100 m; Calif., Mont., Nev., Oreg., Tex., Wyo.; Mexico (Baja California); South America (Chile). Described from Chile, Crassula solieri was overlooked in North America, not distinguished from C. aquatica before it was recognized by M. Bywater and G. E. Wickens (1984).