American Yellowrocket

Herbs biennial or perennial, (10-)20-60(-100) cm tall. Stems erect, angled, glabrous throughout. Basal and lowermost cauline leaves petiolate; petiole (0.5-)1-5(-7) cm, glabrous or rarely ciliate basally; leaf blade (1-)1.5-4(-6) cm, lyrate-pinnatifid, with (1 or)2-4(-6) lobes on each side of rachis, rarely unlobed, not fleshy; lateral lobes oblong or ovate, 2-10 × 1-5 mm, entire; terminal lobe considerably larger than lateral ones, 1.5-5 × 1-2.5 cm. Cauline leaves usually lyrate-pinnatifid, with 1-4 lateral lobes, rarely coarsely toothed, sessile, conspicuously auriculate; auricles ovate or narrowly oblong, to 8 × 5 mm, ciliate, entire; lateral lobes oblong or ovate, rarely lanceolate, to 2 × 1 cm, glabrous, entire; terminal lobe much larger than lateral ones, to 5 × 3 cm, entire, repand, or rarely dentate. Racemes ebracteate, elongated considerably in fruit. Sepals yellow, oblong, 2.5-3.5 × 1-1.5 mm, erect, margin scarious, lateral pair slightly saccate. Petals yellow or pale yellow, oblanceolate, rounded, (3-)4-5(-6) × 1.5-2 mm, attenuate to base. Filaments yellow, 3-4.5 mm; anthers oblong, ca. 1 mm. Fruiting pedicels erect or ascending, (2-)3-6(-7) mm, terete or subquadrangular, glabrous, stout, slightly narrower than fruit. Fruit linear, (1.5-) 2-4(-5) cm × 1.2-1.5 mm, terete-subquadrangular, torulose, erect to erect-ascending; gynophore to 0.3 mm; valves apex obtuse to subacute; style stout, 0.5-1(-1.2) mm. Seeds brown, ovate or oblong, 1.2-1.5 × 0.9-1 mm, uniseriate, somewhat plump, wingless. Fl. Jun-Jul, fr. Aug-Sep. 2n = 16.

Gansu, Heilongjiang, Jilin, Liaoning, Nei Mongol, Taiwan, Xinjiang [Japan, Korea, Mongolia, Russia; North America].

Open grasslands, scree, temperate mixed forests, river and streamsides, moist grassy slopes; 400-2100 m.

Barbarea americana Rydberg; B. cochlearifolia H. Boissieu; B. hondoensis Nakai; B. orthoceras var. formosana Kitamura; B. patens H. Boissieu; B. vulgaris R. Brown var. orthoceras (Ledebour) Regel.