18. Draba L. (whitlow wort, whitlow grass)

Plants annual or biennial (perennial or woody elsewhere), terrestrial, variously pubescent with unbranched to branched and/or stellate hairs. Stems erect or ascending. Leaves basal and/or alternate, sessile or short-petiolate, not clasping (clasping elsewhere), simple, the margins entire or shallowly toothed. Inflorescences racemes, few-branched panicles, rarely appearing nearly umbellate, the flowers not subtended by bracts (with bracts elsewhere). Sepals lanceolate to elliptic or ovate, erect or spreading, green. Petals shallowly to deeply 2-lobed at the tip or unlobed and rounded, white (yellow, lavender, or purple elsewhere), rarely absent. Styles absent or less than 0.3 mm long (to 17.0 mm elsewhere). Fruits ascending, 2–5 times (to more than 40 times elsewhere) as long as wide, flattened parallel to the septum (circular in cross-section elsewhere), dehiscent longitudinally. Seeds in 2 rows in each locule, 0.5–1.5 mm long (longer elsewhere), ovate to broadly elliptic in outline, the margins not winged, the surface finely pebbled or warty, sometimes faintly reticulate, yellow to light orange. About 350 species, nearly worldwide, except for the Australian region, mostly temperate to arctic.

Draba is the largest genus in the family Brassicaceae. Rollins (1993) included more than 100 species from North America, most of these from the western and northern portions of the continent.