3. Arabidopsis Heynh.

(O’Kane and Al-Shehbaz, 1997)

Plants annual or perennial herbs, terrestrial, with simple and 2- or 3-branched, stalked hairs. Stems 2–45(–80) cm long, erect to loosely ascending from a spreading base, branched at the base or unbranched. Leaves alternate and basal, 1–6(–10) cm long, the bases not clasping, the margins entire, toothed, or pinnately divided. Inflorescences racemes, without bracts. Sepals 1.0–3.5 mm long, erect or ascending, oblong. Petals entire or notched at the tip, white, pink, or purple. Styles 0.5–1.5 mm long. Fruits spreading or ascending, 1.0–4.5 cm long, to 50 times as long as wide, linear, circular in cross-section or flattened parallel to the septum, dehiscing longitudinally, the valves with or without a midnerve. Seeds 8–35 per locule, 0.3–1.4 mm long, oblong or elliptic in outline, sometimes slightly flattened, brown. Nine species, North America, Europe, Asia.