Drabas or whitlow-grasses are annual or biennial to strongly perennial, leafless to leafy-stemmed herbs with entire to toothed, simple leaves, hairless to copiously short-hairy with branched to star-shaped or sometimes simple hairs.
The flowers are arranged in clusters that are bractless or sometimes partially with bracts at flower bases. The 4 sepals are erect or spreading at the tip, only slightly if at all pouch-shaped at the base. The 4 petals are white or yellow in our species, rounded to 2-lobed or just notched at the tip, with a lower, narrower part called the claw. The annual species often have flowers of 2 different forms. There are 6 stamens, the anthers ovoid to oblong-ovoid, not coiling after opening. The fruit pods are short, linear to ovate, strongly compressed to considerably inflated, hairless to densely short-hairy, plane to sometimes twisted. Style is lacking to very prominent and usually slender. There are generally numerous seeds, occasionally only 1-2, arranged in 2 rows, usually somewhat flattened and sometimes wing-edged, not slimy when wet.
The genus has nearly 300 species, mostly in temperate to arctic N. America and Eurasia, a few in S. America. The annual species are often found in rather various habitats, the perennial species are usually montane, at least in our area. The name is adopted from Dioscorides, who first used the word, drabe, meaning acrid, for some member of the family. Several of the Eurasian perennials are valued rock garden plants, but some are difficult to grow.