Barbarea vulgaris aka Winter Cress

Barbarea vulgaris is a mustard-family herb known as yellowrocket or wintercress. Its native range spans Europe and the Mediterranean to Japan. It is native to Britain and Ireland as well. It also grows in Canada and the United States. It lives in damp places, along roads, streams, and hedges. Plants grow as biennials or short-lived perennials in temperate climates.

Garden plants reach 1.3–3 feet [0.4–0.9 metres] tall. They spread about 0.8–1.5 feet [0.25–0.45 metres] wide. A leaf rosette forms in the first year. Upright flower stems rise in the next growing season. The stout stems have angles and branch near the top. They range from pale green to reddish purple. The dark green leaves lack hairs and have shiny tops. Basal leaves are pinnate, with a large end lobe. Smaller leaves grow alternately up the stems and clasp them. A thick taproot makes mature plants hard to move.

Small yellow flowers open from mid-spring into early summer. The display lasts about a month and has a light scent. Each flower has four petals and six stamens. Flowers open near the tops of the racemes. Slender seedpods form below them on the same stems. These siliques point upward and end in short beaks. They hold brown seeds that are slightly flat. Bees, butterflies, and hoverflies visit the flowers for food.

Grow this plant in sun or light shade. It needs moist soil that drains well. Fertile loam or clay-loam supports stronger growth than poor, dry ground. It also accepts sandy soil and a range of pH levels. Most leaf growth takes place during cool spring weather. Mild winters allow growth to continue through the colder months. Sources give USDA hardiness ranges of 5–9 and 3–9. It needs little care and grows at a moderate rate. Seed offers a way to raise new plants. It suits borders, rock walls, and gardens for pollinators. It seeds freely and may form patches on damp, disturbed ground. NC State reports no known diseases or insect pests.

Young leaves can be eaten raw or cooked. They have a sharp, peppery taste; older leaves taste stronger. Flowers and young flower stems also have food uses. Mild weather can keep leaves available through winter. Reports link eating the leaves with harm to kidney function. Past uses include leaf poultices for wounds and medicinal teas. These records do not establish that such treatments are safe. The ASPCA lists the plant as toxic to horses. Its isothiocyanates can cause gut irritation and colic. The same source lists it as non-toxic to cats and dogs.