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Biennials or perennials; usually glabrous, except blade auricles often ciliate. Stems (1-)2-6 (-10) dm. Basal leaves: petiole (0.5-)1-7(-15) cm, (rarely ciliate basally); blade usually lyrate-pinnatifid, (1-)1.5-6(-11) cm, lobes (0, 1, or) 2-4 (or 5) on each side, lateral lobes oblong or ovate, 0.2-1 cm × 1-5 mm, not fleshy, margins entire, terminal lobe 1.5-5 cm × 10-25 mm. Cauline leaves: blade usually lyrate-pinnatifid (sometimes undivided and margins coarsely toothed or subentire), lateral lobes 1-4, (usually oblong or ovate, rarely lanceolate, to 2 × 1 cm), margins entire, (terminal lobe to 5 × 3 cm, margins usually entire or repand, rarely dentate); conspicuously auriculate, auricles ovate or narrowly oblong, (to 8 × 5 mm, margins entire). Fruiting pedicels erect or ascending, (2-)3-6(-7) mm, terete or subquadrangular, stout, (narrower than fruit). Flowers: sepals 2.5-3.5 × 1-1.5 mm, lateral pair slightly saccate basally, margins scarious, (subapically sparsely pubescent or glabrous); petals yellow or pale yellow, oblanceolate, 5-7(-8) × (1.5-)2-3 mm, base attenuate, apex rounded; filaments 3-4.5 mm; anthers 1 mm; ovules (24-)26-36 per ovary; gynophore to 0.5 mm. Fruits erect to erect-ascending, rarely appressed to rachis, torulose, terete to subquadrangular, (2.5-)3.1-4(-4.5) cm × 1.5-2 mm; style stout, 0.5-1.2(-2) mm. Seeds brown, somewhat plump, ovoid or oblong, 1.2-1.5 × 0.9-1 mm. 2n = 16.
Stems simple or branched above, 3–8 dm; basal lvs simple or with 1–4 pairs of lateral lobes; middle and upper lvs deeply toothed or lyrately lobed, often with 3 or 4 pairs of lfls; pet 3–5 mm; mature pedicels clavate-thickened, to 1 mm; frs erect to spreading, 2–4 cm, the beak 0.5–1.5(–2) mm; 2n=16. Swamps and wet woods; circumboreal, s. in Amer. to Me., N.H., Ont., and Calif. June–July. (B. americana)
A cabbage family herb. It grows up to 60 cm tall. It takes 2 years to complete its life cycle. The stems are simple and unbranched. The leaves near the base have 2-4 small lobes and one large lobe. The leaves on the stem are alternate. The flowers are small and have 4 yellow petals. The flowers are in clusters in the axils of the upper leaves. The fruit is a narrow pod p to 5 cm long.
