Herbs annual, biennial, or perennial, often glabrous and glaucous. Trichomes absent or simple. Stems prostrate or erect, simple or branched. Basal leaves petiolate or subsessile, rosulate or not, simple, entire or dentate. Cauline leaves sessile, often auriculate, sagittate, or amplexicaul at base, entire or rarely dentate. Racemes ebracteate, elongated or not in fruit. Fruiting pedicels slender, divaricate or ascending, rarely reflexed. Sepals ovate or oblong, erect or ascending, base of lateral pair not saccate, margin membranous. Petals white, rarely purple or yellow; blade obovate, oblong, or spatulate, apex obtuse or emarginate; claw differentiated or not from blade. Stamens 6, tetradynamous; filaments dilated or not at base; anthers ovate or oblong, obtuse at apex. Nectar glands 2 or 4, lateral, often 1 on each side of lateral stamen; median glands absent. Ovules 4-24 per ovary. Fruit dehiscent siliques or silicles, linear, oblong, obovate, obcordate, elliptic, lanceolate, or suborbicular, often apically notched, strongly angustiseptate, sessile; valves keeled, winged or wingless; replum rounded; septum complete, membranous, translucent, veinless; style obsolete or prominent, exserted or included in apical notch of fruit; stigma capitate, entire or slightly 2-lobed. Seeds uniseriate, wingless, oblong, ovoid, or ellipsoid, plump; seed coat smooth, reticulate, rugose, or striate, mucilaginous or not when wetted; cotyledons accumbent or rarely incumbent.
About 75 species: temperate Eurasia, especially SW Asia and C and S Europe; six species (two endemic) in China.
Thlaspi was divided by Meyer (Feddes Repert. 84: 449-470. 1970) into 12 genera largely based on seed anatomy. Molecular data provide some support for the recognition of some of Meyer's segregates (e.g., Microthlaspi F. K. Meyer and Noccaea Moench), but such studies are not comprehensive and therefore the traditional broader concept of the genus is tentatively retained in this treatment.
The majority of Chinese and Himalayan material is often difficult to determine to species because of the lack of mature fruit and their remarkable variability in habit, foliage, and flower size.
