Cardamine teres Michaux, Fl. Bor.-Amer. 2: 29. 1803; Erysimum walteri (Elliott) Eaton; Nasturtium micropetalum Fischer & C. A. Meyer; N. obtusum Nuttall; N. palustre (Linnaeus) de Candolle var. tanacetifolium de Candolle; N. tanacetifolium (de Candolle) Hooker & Arnott; N. walteri (Elliott) Alph. Wood; Rorippa obtusa (Nuttall) Britton; R. teres var. rollinsii Stuckey; R. walteri (Elliott) C. Mohr; Sisymbrium teres (Michaux) Torrey & A. Gray; S. walteri Elliott

Annuals or, rarely, biennials; puberulent, at least proximally, or glabrous, (some trichomes clavate to hemispherical, vesicular). Stems (simple or several from base), usually prostrate or decumbent, rarely erect, branched distally, 1-4 dm, (glabrous or pubescent, trichomes vesicular). Basal leaves rosulate; blade margins pinnatifid. Cauline leaves shortly petiolate; blade oblong, oblanceolate to obovate, or lyrate-pinnatisect, (lateral lobes oblong to ovate), (2-)3.5-10(-13.5) cm × 10-40(-53) mm, base auriculate or not, margins usually pinnatifid to pinnatisect, rarely 2-pinnatifid, (lateral lobes) dentate to crenate or sinuate, (surfaces glabrous or adaxially pubescent, trichomes vesicular). Racemes elongated. Fruiting pedicels ascending to horizontal, straight or curved-ascending, (1.5-)2.3-4.7(-5.3) mm. Flowers: sepals erect, oblong, 1.5-2.5 × 0.5-1 mm; petals yellow, spatulate, 1-2 × 0.4-0.7 mm; median filaments 1.2-1.7 mm; anthers ovate, 0.2-0.3 mm. Fruits siliques, straight or curved, linear to oblong-linear, 8-14(-21) × 1-2.5 mm; valves glabrous or pubescent; ovules (100-)150-210 per ovary; style (0.2-)0.5-1.1 mm. Seeds biseriate, reddish brown, cordiform, 0.4-0.5 mm, foveolate.

Flowering Dec-May. Wet areas, muddy grounds, edges of canals and ditches, sandy fields, margins of ponds, streamsides, peat; 0-600 m; Ala., Ark., Fla., Ga., La., Miss., N.C., Okla., S.C., Tex.; Mexico; Central America (Honduras, Nicaragua).