3. Sinapis Linnaeus, Sp. Pl. 2: 668. 1753.
白芥属 bai jie shu
Herbs annual or rarely perennial. Trichomes absent or simple. Stems erect or ascending, often branched apically, leafy. Basal leaves petiolate, not rosulate, simple, lyrate, pinnatifid, pinnatisect, bipinnatisect or/and dentate. Cauline leaves petiolate or sessile, not auriculate, entire, dentate, or shallowly lobed. Racemes ebracteate, elongated considerably in fruit. Fruiting pedicels slender or thickened, erect, ascending, divaricate, or reflexed. Sepals oblong or linear, spreading or reflexed, not saccate. Petals yellow, spreading; blade obovate, apex obtuse or emarginate; claw subequaling sepals. Stamens 6, tetradynamous; anthers oblong, obtuse at apex. Nectar glands 4, distinct; median pair ovoid; lateral pair prismatic, flat, or rarely lobed. Ovules 4-20 per ovary. Fruit dehiscent siliques, linear, lanceolate, or oblong, terete, somewhat 4-angled, or latiseptate, sessile, segmented; valvular segment dehiscent, few to many seeded, longer or shorter than terminal segment, torulose; valves with 3-7, prominent, longitudinal veins, thin or thick and obscurely veined; terminal segment indehiscent, seedless or 1- or 2-seeded, flattened and ensiform, or terete and conical or subulate, sometimes corky; replum rounded; septum complete, membranous; style distinct; stigma capitate, 2-lobed. Seeds uniseriate, wingless, globose, plump or rarely slightly flattened; seed coat reticulate, mucilaginous or not when wetted; cotyledons conduplicate.
Seven species: Mediterranean region, especially N Africa; two species in China.