6a. Arabidopsis lyrata subsp. lyrata; Arabis lyrata Linnaeus, Sp. Pl. 2: 665. 1753; Cardaminopsis lyrata (Linnaeus) Hiitonen, Mem. Soc. Faun. Fl. Fenn. 25: 75. 1950. Type: Canada, D. Kalm s.n. (lectotype designated by O’Kane & Al-Shehbaz (1997: 325), LINN 842.8).
Biennial or perennial herbs, with slender or rarely branched caudex. Basal leaves lyrate-pinnatifid; petioles pilose to subhirsute, often ciliate; lateral lobes 1–5 on each side, entire of few toothed; terminal lobe considerably larger than lateral lobes. Petals 6-8 mm. Fruits 0.7–1 mm wide; styles slender, 0.5–1.1 mm, distinctly longer than broad. 2n = 16, 32.
Habitat: cliffs, calcareous ledges and bluffs, rock crevices, ledges, thickets, sandy areas in open woods, sand dunes, river banks, sandstone hills, serpentine rocks and barrens, shale, talus.
Elevation: 0–2200 m.
Distribution: Canda (Alberta, British Columbia, Manitoba, Northwest Territoris, Ontario, Saskatchewan), NE European Russia, United States (Alaska, Connecticut, Delaware, District of Columbia, Illinois, Indiana, Iowa, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Tennessee, Vermont, Virginia, West Virginia, Wisconsin).