Tillaea drummondii Torrey & A. Gray, Fl. N. Amer. 1: 558. 1840

Plants terrestrial or subaquatic, annual. Stems decumbent or erect, greenish red in age, diffusely branched, to 10 cm. Leaf blades narrow-lanceolate, 1.5-3 mm, apex obtuse. Inflorescences lax; flowers 1 per node. Pedicels 0.5-3 mm. Flowers 4-merous; sepals triangular-ovate, 0.4-0.6 mm, apex obtuse; petals ovate, 1.3-1.5 mm. Follicles ascending, 9-15-seeded, oblong; old follicles spreading, flat. Seeds oblong to ellipsoid, 0.2-0.4(-0.5) × 0.1-0.3 mm, prickly-papillate, dull, smooth.

Flowering spring. Terrestrial or subaquatic, margins of ponds and streams; 0-50 m; Colo., Kans., S.C., Tex.; South America.

M. Bywater and G. E. Wickens (1984) cited Crassula drummondii also from Arizona; I have referred their specimen (Spring Valley, near Sitgreave Mountain, Lemmon in 1884) to C. viridis (R. V. Moran 1992b).