Description

Key Characters:

Growth Form: Erect annual herbs 2–10 dm tall, usually glabrous throughout, sometimes very sparsely hirsute above.

Stems: Stems unbranched or branched above base.

Roots:

Leaves: Leaves simple. Alternate or rarely opposite. Blades ovate to lanceolate in outline, with an ovate or triangular terminal segment, lateral lobes lanceolate to oblong, usually 6–20 cm long. Margins pinnately lobed. Petioles (0.5–)1–4.5(–6) cm long. Stipules absent.

Flowers: Flowers usually bractless, in dense racemes elongating in fruit. Flowers bisexual (perfect), actinomorphic or rarely slightly irregular. Calyx of 4 sepals, deciduous, erect, usually oblong, sometimes the inner 2 with gibbous bases that hold the nectar. Corolla of 4 petals, pale yellow, fading to almost white before falling, 3–4 mm long, entire to emarginate, rarely lobed or fimbriate, usually with an elongate claw. Stamens 6, tetradynamous, the inner 4 usually in pairs, sometimes connate at base in pairs; anthers dithecal, opening by longitudinal slits. Ovary superior, 2(4?)-carpellate, usually 2-celled by means of a false, but usually complete septum, rarely 1-celled, sessile or rarely stipitate; ovules 1 to numerous, borne on parietal placentas on replum margin at periphery of ovary wall, campylotropous or occasionally anatropous; style 1 or occasionally absent; stigma capitate or rarely decurrent, entire or 2-lobed.

Fruit: Capsules divided into 2 cells by the usually thin and membranous septum; elongate (at least 3 times as long as wide) and referred to as a silique; linear; terete (cylindrical); 3–5 cm long; greater in diameter than the pedicels; dehiscent from the base upward; exposing the septum; sometimes fruit indehiscent or dehiscent and jointed between the seeds; ± breaking up at maturity. Seeds 1 to numerous; oblong; ca. 0.8 mm long; wingless; often becoming mucilaginous when wet; endosperm essentially absent.

Ploidy: 2n = 14; 21; 28; 42; 56

Habitat: naturalized in relatively dry; disturbed areas.

Elevation Range: