Annuals; (terrestrial or of wet habitat, not submerged); densely villous or sparsely hirsute at least basally, sometimes glabrate distally. Stems (simple from base), erect, branched distally, (2-)3-9.5(-11) dm. Basal leaves rosulate; (petiole 1-7 cm); blade margins lyrate-pinnatifid or subruncinate. Cauline leaves sessile; blade lanceolate to oblanceolate or oblong, 2.5-10(-15) cm × 4-25(-45) mm, base auriculate or amplexicaul, margins: proximal lyrate-pinnatifid, (lobes 2-7 on each side), laciniate, irregularly serrate, repand, or entire, distal undivided and entire or obscurely denticulate, (apex acute). Racemes considerably elongated. Fruiting pedicels ascending, straight, (2-)4-12(-14) mm, (glabrous or hirsute). Flowers: sepals spreading, oblong, 1.6-2.8 × 0.6-1.2 mm; petals yellow, obovate or spatulate, (1.5-)1.8-3(-3.5) × 0.7-1.8(-2) mm; median filaments 1.5-2.5 mm; anthers oblong, 0.5-0.6 mm, (gynophore 0.3-0.8(-1) mm). Fruits silicles, straight, globose or subglobose, (2.5-)3.5-6(-6.5) × (2.3-)2.8-4(-4.3) mm; valves [(3 or) 4(-6), leathery, not veined], glabrous; (septum fenestrate at middle); ovules 60-85 per ovary; style (stout), 0.5-1(-1.4) mm. Seeds dark reddish brown, oblong-ovate, 0.5-0.7 mm (0.3-0.4 mm diam.), reticulate. 2n = 16.

Flowering Jun-Aug. Forest borders, roadsides, waste grounds, moist areas, stream banks, gravel pits; 100-700 m; Sask., Yukon; Alaska; e Asia.

Rorippa barbareifolia is readily distinguished from other species of the genus by having fruits consistently with more than two valves. Other species (e.g., R. calycina, R. palustris) occasionally show three-valved fruits, but these always appear with more, normal, two-valved fruits on the same plant.