3. Arabidopsis lyrata (Linnaeus) O’Kane & Al-Shehbaz, Novon. 7: 325. 1997.
Arabis lyrata Linnaeus, Sp. Pl. 2: 665. 1753; Cardaminopsis lyrata (Linnaeus) Hiitonen
Biennials or perennials; (caudex branched or not, sometimes root crown present); glabrous or pubescent, trichomes simple, with stellate, forked, and rayed ones. Stems simple or few to several from base, erect or decumbent, usually branched distally, 0.5-5 dm, pubescent basally, trichomes mixed simple, 1-forked, and (fewer) stellate ones, rarely 3-rayed, glabrous or pubescent apically. Basal leaves: petiole 0.5-6 cm; blade oblanceolate or ovate, 0.5-8.5 cm × 2-18 mm, margins entire, dentate, or lyrate-pinnatifid (when lobed, terminal lobes larger than lateral), apex obtuse, surfaces glabrous or sparsely to densely pubescent. Cauline leaves shortly petiolate or sessile; blade oblanceolate, 0.4-4.2 cm × 1-8(-10) mm (smaller distally), margins usually entire, repand, or obscurely toothed, rarely lobed. Fruiting pedicels divaricate or ascending, 2-15 mm. Flowers: sepals 2-4.5 mm, lateral pair saccate basally, (glabrous or densely pubescent); petals white or purplish, spatulate or obovate, 4-10 × 1.5-4 mm, (claw to 2 mm, toothless); filaments 2-4 mm. Fruits torulose, flattened, (1.5-)2-4.5 cm × 0.8-1.8 mm; valves each with distinct midvein; ovules 24-46 per ovary; style 0-1 mm. Seeds light brown, (flattened), oblong, 0.8-1.4 mm; cotyledons accumbent.
Subspecies 3 (3 in the flora): North America, n Europe, n, e Asia.