Thlaspi

Plants often fetid when crushed; not scapose; glabrous or pubescent. Stems erect, unbranched or branched distally. Leaves basal and cauline; petiolate or sessile [subsessile]; basal (often withered in fruit), rosulate or not, petiolate [subsessile], margins entire, repand, dentate, or sinuate-dentate; cauline sessile, blade (base auriculate or sagittate), margins dentate, repand, or entire. Racemes (several-flowered), considerably elongated in fruit. Fruiting pedicels divaricate, (straight or slightly curved), slender. Flowers: sepals erect or ascending, ovate or oblong, (margins membranous); petals spatulate [oblong], claw differentiated or not from blade, (apex obtuse or emarginate); stamens slightly tetradynamous; filaments not dilated basally; anthers ovate, (apex obtuse); nectar glands (2 or 4), lateral, often 1 on each side of lateral stamen, median glands absent. Fruits silicles, sessile, oblong, obovate, obcordate, or suborbicular, (apex often notched), keeled, strongly angustiseptate; valves winged throughout or apically, glabrous; replum rounded; septum complete, (not veined); ovules 6–16 per ovary; style obsolete or not, (included in apical notch); stigma capitate. Seeds plump, not winged, ovoid; seed coat (coarsely reticulate, alveolate or concentrically striate), not mucilaginous when wetted; cotyledons accumbent. x = 7.

Distribution

Eurasia, n Africa, introduced also nearly worldwide.

Discussion

Species 6 (2 in the flora).

Thlaspi was divided by F. K. Meyer (1973) into 12 genera largely based on seed-coat sculpture and anatomy. Molecular data (K. Mummenhoff et al. 1997; M. Koch and Mummenhoff 2001) showed that Thlaspi is polyphyletic and strongly supported some of Meyer’s segregates, including Microthlaspi and Noccaea, both of which are recognized in this flora. As here delimited, Thlaspi consists of six species (Meyer), instead of over 75 recognized by various authors.

Selected References

Koch, M. and K. Mummenhoff. 2001. Thlaspi s.str. (Brassicaceae) versus Thlaspi s.l.: Morphological and anatomical characters in the light of ITS nDNA sequence data. Pl. Syst. Evol. 227: 209–225.

Meyer, F. K. 1973. Conspectus der “Thlaspi”-Arten Europas, Afrikas und Vorderasiens. Feddes Repert. 84: 449–470.

Meyer, F. K. 1979. Kritische Revision der “Thlaspi”-Arten Europas, Afrikas und Vorderasiens: I. Geschichte, Morphologie und Chorologie. Feddes Repert. 90: 129–154.

Meyer, F. K. 2001. Kritische Revision der “Thlaspi”-Arten Europas, Afrikas und Vorderasiens. Spezieller Teil. I. Thlaspi L. Häussknechtia 8: 3–42.

Mummenhoff, K., A. Franzke, and M. Koch. 1997. Molecular phylogenetics of Thlaspi s.l. (Brassicaceae) based on chloroplast DNA restriction site variation and sequences of the internal transcribed spacers of nuclear ribosomal DNA. Canad. J. Bot. 75: 469–482.

Lower Taxa

Thlaspi alliaceum, Thlaspi arvense

Key

1	Plants glabrous throughout; fruits broadly winged throughout, wing 3.5-5 mm wide apically; seeds concentrically striate.	Thlaspi arvense
1	Plants sparsely to densely pubescent basally along stems; fruits obscurely winged basally, wing to 1 mm wide apically; seeds alveolate.	Thlaspi alliaceum