Arabidopsis thaliana (L.) Heynh.

Arabidopsis species are annual, biennial or perennial herbs. Trichomes simple, stalked 1-3 forked. Stem erect or decumbent, several, much branched from the base. Basal radical leaves rosulate, oblong to oblanceolate, margin entire or dentate, glabrous or pubescent, petiolate, cauline leaves sagittate, margin entire, dentate or lyrate, base cuneate, petiole subsessile or sessile. Inflorescence racemes, terminal, few to several flowered, lax in fruit, ebracteate. Flowers bisexual, white, pink or purple, actinomorphic, pedicel slender, sepals 4, spreading, oblong or ovate, glabrous or pubescent, basal pair subsaccate or not, petals 4, spathulate-obovate, margin entire, apex obtuse, almost twice long as than sepals. Stamens 6, slightly tetradynamous, filaments not dilated at the base, anthers oblong-linear, nectar glands annular or semiannular, middle gland often torulose, ovary superior, bicarpellary, syncarpous, linear, ovules 10-70, stigma depressed. Fruit siliqua, dehiscent, linear or cylindric, curved, terete or compressed, valves papery, weakly or distinctly midveined, torulose or smooth, style short or obsolete. Seeds few to many, uniseriate or biseriate, orbicular-ovate, compressed, smooth or minutely reticulate, cotyledons accumbent, sometimes incumbent.

Arabidopsis species flowers are complete, bisexual, i.e., with functional male (androecium) and female (gynoecium), including stamens, carpels and ovary. Pollination is entomophilous i.e., by insects, or cleistogamy i.e., by self or allogamy i.e., by cross pollination. Flowering/Fruiting: April-June.

Seeds may be dispersed by autochory i.e., self dispersal, anemochory i.e., wind dispersal, zoochory i.e., dispersal by birds or animals, anthropochory i.e., dispersal by humans.

Annual herbs, sparsely hispid with simple or forked hairs, about 5-35 cm tall. Stem erect, 1 to few from the base, further branched or simple above. Basal radical leaves in rosette, oblong, oblanceolate, about 1.5-7.5 x 0.3-0.9 cm across, base attenuate, margin entire or shallow dentate, apex obtuse or rounded, petiole short to subsessile, cauline leaves smaller, linear lanceolate to linear oblong, about 0.5-1.2 x 0.1-0.25 cm across, base attenuate to cuneate, margin entire or rarely slightly dentate, apex obtuse, petiole sessile. Inflorescence racemes, terminal, 10-30 flowered, about 10-20 cm long, lax in fruit, ebracteate. Flowers bisexual, white, actinomorphic, about 0.2-0.3 cm across, pedicel slender, spreading or descending, about 0.6-0.8 cm long, sepals 4, erect or spreading short, ovate, glabrous or sparsely pubescent, lateral pair not saccate, about 1-2 mm long, petals 4, spathulate-obovate, base attenuate, margin entire, apex obtuse, about 3-4 mm long. Stamens 6, slightly tetradynamous, filaments not dilated at the base, anthers oblong-linear, nectar glands annular or semiannular, ovary superior, bicarpellary, syncarpous, linear, ovules 40-70, stigma depressed. Fruit siliqua, dehiscent, linear or cylindric, terete, curved, compressed, valves papery, distinctly midveined, torulose, style abput 0.5 mm long. Seeds 20-40, orbicular-ellipsoid, compressed, minutely reticulate, glabrous or minutely reticulate, cotyledons incumbent.

Arabidopsis species are susceptible to insect pests, virus, mildews and rusts.

Along sides of the streams and moist grassy slopes, altitude 800-3500 m.

Not evaluated (IUCN).

This species is a model in plant genetic studies.