General:
Annual, biennial, or short-lived perennial herb from a slender taproot; stems erect, 15-100 cm tall, simple to much branched from base, glabrous to stiff-hairy.

Leaves:
Basal and lower stem leaves oblong to oblanceolate, (4) 6-20 cm long, 0.5-4 cm wide, short-stalked to unstalked, irregularly saw-toothed, incised, deeply cleft, repand, or variously pinnately divided, with slightly clasping, ear-like lobes at the bases, sharp- or long-pointed at the tips; glabrous or stiff-hairy.

Flowers:
Inflorescence of spreading-ascending stalks, 3-14 mm long, glabrous to sparsely hairy; petals light yellow, 1-3.5 mm long, oblong to broadly spoon-shaped; sepals often yellowish or purplish, 1-2 mm long, glabrous.

Fruits:
Siliques, spreading to ascending, straight to somewhat upcurved, 3-14 mm long, 2-3 mm wide, egg-shaped to cylindric or clavate, 1- to 4-carpelled; beaks 0.2-1 mm long, straight, abruptly attached to apex; seeds brown to reddish-brown, mostly 0.4-0.6 mm long, minutely honeycombed and pimpled, 20-80.

Notes:
At least six poorly defined varieties have been attributed to the BC flora, but are not treated here.

Source:  The Illustrated Flora of British Columbia

Synonyms and Alternate Names:
Radicula palustris (L.) Moench
Rorippa islandica var. microcarpa (Regel) Fernald
Rorippa palustris subsp. palustris
Rorippa palustris var. reptabunda (Fernald) R. Stuckey
Rorippa palustris var. williamsii (Britton) Hultén