Perennial herb 20 cm - 0.6 m tall Stem: upright, branched or unbranched, green, purplish near base, mostly hairless. Flowers: in rounded, branched clusters, white, 7 mm - 1.5 cm wide. Sepals four, green, turning yellowish with age. Petals four, much longer than sepals. Stamens six. Fruit: a narrow pod, upright, ascending to diverging, 1.5 - 2.5 cm long, lance-shaped, somewhat flattened, with a 2 - 4.5 mm beak. Rhizome: short, stout, tuber-like, barely subterranean. Lower leaves: alternate, long-stalked (purplish), 2.5 - 5 cm long, 2.5 - 3 cm wide, oval to egg-shaped to roundish, base tapering to truncate (cut straight across), slightly wavy along the margins, sometimes hairy. These leaves usually fall off before the plant begins to flower. Upper leaves: alternate, mostly stalkless, smaller than basal leaves, oblong to lance-shaped, sometimes coarsely toothed, sometimes hairy.
Similar species: The similar Cardamine pratensis and C. pratensis var. palustris differ by having pinnately divided leaves. Cardamine douglassii differs by having mainly hairy stems, pink or purple-tinged flowers, and sepals that turn purplish. Also, the blooming period of C. douglassii ends by mid-May. Other Cardamine species will have petals less than 7 mm long.
Flowering: mid-April to late June
Habitat and ecology: Typical of calcareous fens, but also found in moist woods and floodplains. Also grows along roads, rivers, creeks, and other wet areas.
Occurence in the Chicago region: native
Etymology: Cardamine comes from the Greek word kardamon, which refers to plants in the cress family. Bulbosa means bulbous.
Stems borne singly or few together from a short, stout, tuber-like, barely subterranean rhizome, simple or branched above, 2-4.5 dm to the first fl, the raceme elongating at anthesis so that the whole pl may reach 6 dm; lvs all simple, the lower long-petioled, the 4-8 cauline ones progressively less so or sessile; basal blades rotund or cordate, mostly about as wide as long, only rarely purplish beneath, generally deciduous before anthesis; cauline blades narrowly oblong to ovate; herbage sparsely to copiously beset with very short hairs to 0.15(0.2) mm; sep green, turning yellow after anthesis; pet white (rarely pink), 7-16 mm; pedicels at maturity ascending to divergent, the lower to 4 cm; fr slender, 1.5-2.5 cm, often abortive, its beak 2-4.5 mm; 2n=64, 80, 96. Moist or wet woods or shallow water; Que. to Minn., S.D., and Kans., s. to Fla. and Tex. Apr.-June. (C. bulbosa
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.