Annuals; usually glabrous, rarely sparsely pubescent. Stems erect, unbranched or branched proximally or distally, (0.6-)2-6(-7.5) dm. Basal leaves not rosulate; blade margins pinnatifid. Cauline leaves petiolate (to 4 cm) or (distal) sessile; blade lyrate-pinnatipartite or undivided, obovate, oblong, or lanceolate, (lobes 0 or 1-5 (or 6) on each side), (2.5-)3.5-12(-16) cm × (8-)15-40(-50) mm, base auriculate or not, margins entire, irregularly crenate, or serrate, (entire or denticulate distally). Racemes elongated. Fruiting pedicels usually ascending or divaricate, rarely slightly reflexed, straight, (2-) 3-10(-15) mm. Flowers: sepals ascending, oblong-ovate, 2-3 × 0.8-1.5 mm; petals yellow, obovate or spatulate, (2.5-)3-4(-4.5) × 1-1.5 mm; median filaments 1.5-3 mm; anthers oblong, 0.5-0.8 mm. Fruits siliques, often curved-ascending, linear, (7-)10-24(-30) × 1-1.5(-2) mm; ovules (60-)70-110 per ovary; style (0.5-)1-1.5(-2) mm, (slender, narrower than fruit). Seeds biseriate or nearly so, reddish brown, ovate or ovate-orbicular, 0.5-0.9 mm (0.4-0.6 mm diam.), foveolate. 2n = 16, 24, 32, 48. Flowering most of the year. Roadsides, wet places, field margins, gardens, streamsides, ditches, flood plains, waste grounds; 0-200[-3200] m; introduced; B.C.; La., Miss., N.Y., Oreg.; Asia; introduced also in Central America, South America. Nasturtium indicum (Linnaeus) de Candolle 1821, not Garsault 1764 is a combination and a later homonym of Rorippa indica.
Low perennial 1-3 dm, essentially glabrous throughout; lvs mainly cauline, the principal ones petiolate, with lance-elliptic to lance-rhombic, merely toothed blade to 7 נ2 cm; pet 3 mm, slightly surpassing the sep; mature pedicels widely ascending; frs cylindric, upcurved, 1 cm, with a short, thick stylar beak 0.5(-1) mm. Native of se. Asia, sparingly intr. as a weed in N.Y. and elsewhere. May, June.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.