Tillaea viridis S. Watson, Proc. Amer. Acad. Arts 23: 272. 1888

Plants aquatic, annual. Stems decumbent, dark yellowish in age, branched, 5-7 cm. Leaf blades linear, 3-12 mm, apex narrowly acute or attenuate. Inflorescences lax; flowers 1 per node. Pedicels 0.5-6 mm. Flowers 4-merous; sepals triangular-ovate, 0.7-0.8 mm, apex obtuse; petals triangular, 1.3 mm. Follicles ascending, 6-12-seeded, obliquely sublanceolate; old follicles spreading, flat. Seeds oblong to narrowly reniform, 0.4-0.6 × 0.1-0.3 mm, papillate, dull, rugose.

Flowering spring. Terrestrial or aquatic, margins of pools and streams; of conservation concern; 2100-2500 m; Ariz., Idaho; Mexico; South America (Brazil).

Crassula viridis occurs in the flora area on the Mogollon Rim of Arizona and near Priest River in Conner County, Idaho.