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.