Cardamine oligosperma

Annuals or biennials; usually sparsely hirsute (at least proximally), rarely glabrous. Rhizomes absent. Stems (simple or few from base), erect to ascending, (not flexuous), unbranched or branched distally, (0.5-) 0.8-3.2(-4.1) dm, usually pubescent throughout or proximally, rarely glabrous. Basal leaves (persistent to anthesis), rosulate, pinnately compound, 5-9(-13)-foliolate, 2-8.5(-11) cm, leaflets petiolulate or subsessile; petiole 1-6 cm; lateral leaflets petiolulate or subsessile, blade obovate to oblanceolate, smaller than terminal, margins entire or crenate; terminal leaflet (petiolule 0.1-0.7 cm), blade usually orbicular to ovate, rarely oblong, 0.4-1.5(-2.3) cm × 3-10(-13) mm, base cordate to rounded, margins entire, or crenate-dentate to obscurely 3 or 5-lobed, (surfaces often hirsute, sometimes glabrous). Cauline leaves 3-8, pinnately compound, similar to basal, smaller and fewer distally, petiolate, leaflets petiolulate or subsessile; petiole 0.5-2 cm, base not auriculate. Racemes ebracteate. Fruiting pedicels divaricate-ascending, (2-)3-9(-12) mm. Flowers: sepals oblong, 1.3-1.8(-2) × 0.5-1 mm, lateral pair not saccate basally; petals white, narrowly spatulate to oblanceolate, 2.5-3.5 × 0.9-1.5 mm (not clawed); filaments: median pairs 1.7-2.5 mm, lateral pair 1.2-2 mm; anthers ovate, 0.3-0.5 mm. Fruits linear, (torulose), (1.3-)1.6-2.8 cm × 1-1.7 mm; (valves glabrous or sparsely pubescent); ovules 16-36(-42) per ovary; style 0.4-1(-1.5) mm. Seeds brown, oblong, 1-1.6 × 0.8-1.2 mm. 2n = 16.

Flowering Mar-Jul. Stream banks, shady banks, creek bottoms, lakeshores, meadows, moist areas, wooded slopes; 50-3300 m; B.C.; Calif., Colo., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo.; Mexico (Baja California).