四齿芥 si chi jie shu

Tetracmidion Korshinsky.

Herbs annual, canescent. Trichomes stalked, stellate or dendritic, rarely mixed with fewer, simple or forked, subsetose ones. Stems often several branched basally. Basal leaves petiolate, not rosulate, simple, entire, sinuate-dentate, or pinnatipartite. Cauline leaves similar to basal. Racemes ebracteate, corymbose, elongated in fruit. Fruiting pedicels slender or thickened and nearly as wide as fruit base, erect or ascending. Sepals ovate, ascending, base of lateral pair not saccate, margin membranous. Petals white, subequaling or much longer than sepals; blade obovate, spatulate, or oblanceolate, apex obtuse; claw distinct or undifferentiated from blade. Stamens 6, slightly tetradynamous; filaments dilated at base; anthers ovate, apiculate at apex. Nectar glands 4, lateral, 1 on each side of lateral filament; median glands absent. Ovules 2-14 per ovary. Fruit dehiscent siliques or indehiscent silicles, linear, oblong, or ovoid, strongly latiseptate, terete, or 4-angled, sessile; valves obscurely veined, tomentose, smooth or torulose, subapically 4-horned; replum flattened; septum complete, membranous; style absent, obsolete, or distinct; stigma capitate, entire. Seeds uniseriate, wingless, oblong, plump; seed coat smooth, not mucilaginous when wetted; cotyledons incumbent.

Eight species: primarily in C Asia; two species in China.

Lower Taxa

• Tetracme quadricornis (Stephan) Bunge
• Tetracme recurvata Bunge