4. Diplotaxis de Candolle, Mém. Mus. Hist. Nat. 7: 243. 1821.
二行芥属 er hang jie shu
Herbs annual or perennial. Trichomes absent or simple. Stems erect or ascending, rarely procumbent. Basal leaves petiolate, rosulate or not, dentate, lyrate, pinnatifid, or pinnatisect, rarely bipinnatipartite. Cauline leaves petiolate or sessile and sometimes auriculate. Racemes ebracteate or rarely lowermost flowers bracteate, elongated in fruit. Fruiting pedicels ascending, divaricate, or recurved. Sepals oblong or linear, erect or spreading, base of lateral pair often not saccate. Petals yellow, white, pink, or purple, longer than sepals; blade obovate or suborbicular, apex obtuse or emarginate; claw absent or as long as or shorter than sepals. Stamens 6, tetradynamous; filaments not dilated at base; anthers oblong, obtuse at apex. Nectar glands 4; median glands large; lateral glands smaller. Ovules 16-260 per ovary. Fruit dehiscent siliques, linear, latiseptate or terete, glabrous, sessile or long stipitate, unsegmented or segmented; valvular segment well developed, dehiscent, numerous seeded, much longer than terminal segment, torulose, with a distinct midvein; terminal segment indehiscent, seedless or 1- or 2-seeded; replum rounded; septum complete; style obsolete to 4 mm; stigma capitate, entire or 2-lobed. Seeds biseriate, wingless, oblong, ovoid, or ellipsoid, slightly flattened; seed coat smooth or minutely reticulate, slightly mucilaginous or not mucilaginous when wetted; cotyledons conduplicate.
About 30 species: especially in NW Africa, the Iberian Peninsula, and Macaronesia, extending into C Asia; one species (introduced) in China.