Plants annual, slender, glabrous or pubescent.
Stems somewhat flexuous, (5)10–30(40) cm.
Basal leaves often withered by anthesis, not rosulate, pinnately (5)7–13(17)-foliolate, (2)4–10 cm, terminal leaflets linear, oblong, oblanceolate, obovate, or suborbicular, (1)3–10 × 1–7 mm, margins entire, or 3(5)-toothed or -lobed, lateral leaflets similar to terminal.
Cauline leaves pinnately or palmately compound, (5)9–15(17)-foliolate, bases not auriculate, lateral leaflets narrowly oblong, linear, or filiform, 1–3 mm wide, terminal leaflets filiform, linear, or narrowly oblong, 3–10(16) × 0.3–3 mm, margins entire or rarely 1–3-toothed.
Inflorescences bracts 0; fruiting pedicels divaricate or ascending, 4–10 mm.
Flowers sepals oblong, 1–1.5(2) mm; petals oblanceolate, (1.5)1.8–2.5(3) × 0.4–0.8(1) mm, white; stamens 6, anthers ovate, 0.2–0.4 mm; ovules 20–50 per ovary, styles 0.3–0.7(1) mm.
Fruits (5)10–20(25) × 0.6–0.9 mm, glabrous.
Seeds oblong-ovate, 0.6–0.9 × 0.4–0.6 mm, margined or not.
2n=16.
Roadsides, riverbanks, rocky crests and outcrops, dry woods, fallow fields, marsh and swamp margins, floodplains, waste grounds, ledges and cliffs. Flowering Apr–Jun. 0–1300 m. BW, WV. WA; throughout southern Canada, central and eastern US. Native.
as described under Cardamine parviflora
Annuals; (slender); glabrous or sparsely to densely pubescent throughout. Rhizomes absent. Stems (simple or few to several from base), erect, (somewhat flexuous), often branched distally, (0.5-)1-3(-4) dm. Basal leaves (often withered by anthesis), usually not rosulate, pinnately (5 or) 7-13(-17)-foliolate, (2-)4-10 cm, leaflets sessile or petiolulate; petiole 0.5-2.5(-4.5) cm; lateral leaflets similar to terminal, sometimes smaller; terminal leaflet (sessile or petiolule to 0.5 cm), blade linear to oblong, oblanceolate to obovate, or suborbicular, (0.1-)0.3-1 cm × 1-7 mm, base cuneate, margins entire or 3(-5)-toothed or -lobed. Cauline leaves 5-10(-14), (5-)9-15(-17)-foliolate, petiolate, leaflets sessile; petiole 0.3-1 cm, base not auriculate; lateral leaflets similar to terminal, sometimes smaller; terminal leaflet blade filiform, linear, or narrowly oblong, 0.3-1(-1.6) cm × 0.3-3 mm, margins usually entire, rarely 1-3-toothed. Racemes ebracteate. Fruiting pedicels divaricate or ascending, 4-10 mm. Flowers: sepals oblong, 1-1.5(-2) × 0.3-0.5 mm, lateral pair not saccate basally, (margins membranous); petals white, oblanceolate, (1.5-)1.8-2.5(-3) × 0.4-0.8(-1) mm; filaments 1.4-2.5 mm; anthers ovate, 0.2-0.4 mm. Fruits linear, (torulose), (0.5-)1-2(-2.5) cm × 0.6-0.9 mm; ovules 20-50 per ovary; style 0.3-0.7(-1) mm. Seeds pale brown, oblong-ovoid, 0.6-0.9 × 0.4-0.6 mm, (narrowly margined or not). 2n = 16.Flowering Mar-Jun. Roadsides, stream banks, rocky crests and outcrops, crevices of granitic bedrock, dry woods, glades, fallow fields, disturbed ground, limestone barrens, marsh and swamp margins, floodplains, waste ground, slopes, ledges, cliffs, meadows; 0-1500 m; Alta., B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.W.T., Ont., Que., Sask.; Ala., Ark., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Oreg., Pa., R.I., S.C., Tenn., Tex., Vt., Va., W.Va., Wis.; Eurasia.Within Cardamine parviflora, in the broad sense, two species or varieties have been recognized: the Eurasian C. parviflora (or C. parviflora var. parviflora) versus the North American C. arenicola (or C. parviflora var. arenicola). Nuclear DNA data suggested a sister relationship of the North American and Eurasian entities, while cpDNA data showed them intermingled (J. Lihová et al. 2006). There are no apparent morphological differences between these entities, although detailed morphological studies are still lacking. We currently prefer to treat them as a single taxon.