Nasturtium sinuatum Nuttall var. columbiae S. Watson in A. Gray et al., Syn. Fl. N. Amer. 1(1,1): 147. 1895; N. columbiae (S. Watson) Suksdorf; N. sinuatum var. pubescens S. Watson; Radicula columbiae (S. Watson) Greene; Rorippa calycina (Engelmann) Rydberg var. columbiae (S. Watson) Rollins; R. sinuata (Nuttall)Hitchcock var. pubescens (S. Watson) Howell

Perennials; (terrestrial or of wet habitat, not submerged, with creeping roots and adventitious stems); pilose or hirsute. Stems suberect or decumbent to prostrate, branched distally, 1-3.2(-4.1) dm, (pilose to hirsute). Basal leaves absent. Cauline leaves shortly petiolate or sessile; blade oblanceolate to oblong, (lateral lobes oblong to ovate, often reaching midrib), 2.4-5.2 cm × 5-12 mm, base auriculate or not, margins sinuate to pinnatifid or (lateral lobes) entire or dentate, (surfaces pilose). Racemes elongated. Fruiting pedicels ascending, (subappressed to rachis), straight, (3-)4-10(-12) mm, (densely pilose). Flowers: sepals (persistent), ascending, oblong, 2-3.5 × 0.8-1.5 mm, (pilose); petals yellow, oblanceolate to spatulate, 2.7-4.2 × 0.7-1.7 mm; median filaments 2-3.5 mm; anthers ovate, ca. 0.8 mm. Fruits silicles, straight, subglobose to oblong ellipsoid, (1.5-)2.5-5.5(-7) × (1-)1.7-2.8(-3.5) mm; valves densely pilose; ovules 24-40 per ovary; style 0.7-3.2 mm, (pilose). Seeds biseriate, yellowish brown, ovoid-globose, 0.7-0.9 mm, prominently colliculate.

Flowering Jun-Aug. Stream banks, ditches, margins of lakes and ponds, meadows, roadsides, gravel bars, wet fields; 100-1600 m; Calif., Oreg., Wash.