Cardamine rotundifolia Michx.
Family: Brassicaceae
American Bittercress
[Cardamine rotundifolia var. diversifolia ]
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Perennials; glabrous throughout. Rhizomes slender, to 2 mm diam. Stems usually procumbent, sometimes erect, (not flexuous), unbranched or branched, (1-) 1.5-3(-5) dm. Rhizomal leaves absent. Basal leaves (soon withered), not rosulate. Cauline leaves simple, petiolate; petiole (0.3-)0.5-2.5(-4) cm, base not auriculate; blade oblong, ovate, suborbicular, or cordate, (0.5-) 1-4.5(-5.5) cm × (5-)10-40(-54) mm, base cordate, rounded, or truncate, margins entire, repand, or sinuate, (distally with shorter petiole, blade smaller). Racemes ebracteate. Fruiting pedicels divaricate to ascending, (6-)10-15(-20) mm. Flowers: sepals oblong, 2-3 × 1-1.7 mm, lateral pair not saccate basally; petals white, broadly oblanceolate, spreading, 5-7(-8) × 2-3 mm, (not clawed, apex rounded); filaments: median pairs 3.5-4.5 mm, lateral pair 2.7-3.5 mm; anthers oblong, 0.8-1.2 mm. Fruits linear, (torulose), 1-1.5(-2) cm × 0.8-1.1 mm; ovules 40-80 per ovary; style 1.5-2.5 mm. Seeds brown, oblong to ovoid, 0.9-1.1 × 0.5-0.6 mm.

Flowering Apr-Jun. Stream banks, swamps, low woodland, wet rocky areas, seepage areas; 150-400 m; Del., Ga., Ky., Md., N.J., N.Y., N.C., Ohio, Pa., Tenn., Va., W.Va.

Stems weak, decumbent or ascending from a long, slender rhizome, emitting stolons with small lvs; larger lvs often with 1 or 2 small lateral lobes on the petiole; cauline lvs mostly petiolate, ovate to rotund, rounded to subcordate at base; pet white, 6-8 mm; raceme and pedicels elongating after anthesis, the pedicels to 1-2 cm; frs divergent or ascending, 1-2 cm, the beak 2.5-3 mm. Wet soil, swamps, or running water; N.Y. and O. to N.C. and Ky. May, June.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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