Photographs: Ballingeary, Co. Cork

American Winter-cress Barbarea verna Treabhach earraigh Family: Brassicaceae Flowering: April-September. Annual or biennial. Introduced. Open racemes of yellow flowers, the flowers approx 5mm across. Fruit is 4-angled or rounded with a stout style, usually 3.5 to 7cm. Pinnate leaves have a large terminal lobe and usually 5-10 pairs of leaflets. Upper stem leaves also pinnate, divided more than halfway to midrib. A very variable plant with erect ridged stems, 30-80cm. Identified by Paul Green, BSBI Infrequent in Ireland on waste and cultivated ground and roadsides Similar: Medium-flowered Wintercress, Barbarea intermedia

American Winter-cress, Barbarea verna, Treabhach earraigh