Arabis thaliana Linnaeus, Sp. Pl. 2: 665. 1753; Sisymbrium thalianum (Linnaeus) J. Gay & Monnard; Stenophragma thalianum (Linnaeus) Celakovsky.

Herbs annual, (2-)5-30(-50) cm tall. Stems erect, 1 or few from base, simple or branched above, basally with predominantly simple trichomes, apically glabrous. Basal leaves shortly petiolate; leaf blade obovate, spatulate, ovate, or elliptic, 0.8-3.5(-4.5) cm × (1-)2-10(-15) mm, adaxially with predominantly simple and stalked 1-forked trichomes, margin entire, repand, or dentate, apex obtuse. Cauline leaves subsessile, usually few; blade lanceolate, linear, oblong, or elliptic, (0.4-)0.6-1.8(-2.5) cm × 1-6(-10) mm, entire or rarely few toothed. Fruiting pedicels slender, divaricate, straight, 3-10(-15) mm. Sepals 1-2(-2.5) mm, glabrous or distally sparsely pubescent with simple trichomes, lateral pair not saccate. Petals white, spatulate, 2-3.5 × 0.5-1.5 mm, base attenuate to a short claw. Filaments white, 1.5-2 mm. Ovules 40-70 per ovary. Siliques linear, terete, smooth, (0.8-)1-1.5(-1.8) cm × 0.5-0.8 mm; valves with a distinct midvein; style to 0.5 mm. Seeds ellipsoid, plump, light brown, 0.3-0.5 mm; cotyledons incumbent. Fl. and fr. Jan-Jun(-Oct). 2n = 10*.

Arabidopsis thaliana is the most widely used flowering plant as a model organism for studies in genetics, development, physiology, biochemistry, and related fields. It is also a naturalized weed throughout much of the world.

Plains, mountain slopes, river banks, roadsides; near sea level to 2000 m. Anhui, Gansu, Guizhou, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Sichuan, Xinjiang, Xizang, Yunnan, Zhejiang [India, Japan, Kazakhstan, Korea, Mongolia, Russia, Tajikistan, Uzbekistan; Africa, SW Asia, Europe, North America].