American yellowrocket

Barbarea orthoceras, commonly known as American yellowrocket or American wintercress, is a biennial or short-lived perennial herb in the family Brassicaceae with a broad circumboreal distribution across northern Asia and most of North America, growing in moist disturbed ground, stream banks, gravel bars, roadside ditches, and meadows from sea level into the subalpine zone. The plant produces a tap-rooted basal rosette of dark green, glossy, lyrate-pinnatifid leaves 5 to 15 centimetres long with a large rounded terminal lobe and one to four pairs of smaller lateral lobes. Flowering stems are erect, glabrous, ribbed, 20 to 70 centimetres tall, with smaller, sessile, clasping, less-divided cauline leaves. The inflorescence is a dense terminal raceme that elongates in fruit, bearing many small bright yellow four-petalled flowers about 6 to 8 millimetres across with six stamens. The fruit is a slender, erect to slightly spreading, four-angled silique 2.5 to 5 centimetres long, terminated by a short straight beak (the orthoceras of the name), splitting at maturity to release small reddish-brown seeds.