Biennials; not scapose. Stems usually branched, rarely unbranched, (0.3-)0.6-3(-4) dm, densely pubescent proximally, trichomes simple, 0.4-1.3 mm, with fewer 2-4-rayed ones, to 0.3 mm, (distally with mostly branched trichomes, with fewer, simple ones). Basal leaves rosulate; petiolate; petiole base and margin ciliate, (trichomes simple, 0.2-0.7 mm); blade lanceolate or oblanceolate to spatulate, 0.5-2.9 cm × 1-5(-9) mm, margins dentate, surfaces pubescent, abaxially with stalked, cruciform, or 2- or 3-rayed trichomes, 0.1-0.4 mm, (rarely with a branched ray), adaxially with simple trichomes, 0.1-0.7 mm, and stalked, 2-4-rayed ones. Cauline leaves (15-)22-54 (-76), (densely imbricate at least basally); sessile; blade ovate to oblong or lanceolate (base often densely bearded abaxially, trichomes simple, to 1.3 mm), margins dentate, surfaces pubescent as basal. Racemes (11-)17-36(-48)- flowered, bracteate basally, elongated or not in fruit; rachis not flexuous, pubescent as stems distally. Fruiting pedicels erect to ascending, (subappressed to rachis), straight, (1.5-)2.5-6(-13) mm, pubescent, trichomes 2-4-rayed and simple. Flowers: sepals ovate, 2-2.5 mm, pubescent, (trichomes simple and short-stalked, 2-4-rayed); petals white, spatulate, 3.5-4.5 × 1-2 mm; anthers ovate, 0.3-0.4 mm. Fruits oblong to linear-lanceolate or elliptic, slightly twisted or plane, flattened, 5-10(-12) × 1.5-2.5(-3) mm; valves glabrous or pubescent, trichomes simple and short-stalked, 2-4-rayed, 0.05-0.3 mm; ovules (24-)30-40 per ovary; style 0.01-0.25 mm. Seeds oblong, 0.7-1.1 × 0.5-0.6 mm. 2n = 32. Flowering Jul-Aug. Rock outcrops, talus, gravelly shores; 0-200 m; Greenland; Man., N.B., Nfld. and Labr., Ont., P.E.I., Que.; Mich., Minn.; n, c Europe (Russia).
Biennial, producing the first year a rosette that elongates the second year into a leafy flowering stem, the cauline lvs usually very numerous, not strongly contrasting with the basal, gradually reduced upwards, the foliage forming a narrow cone; basal lvs narrowly oblanceolate, to 3 cm נ5 mm, the cauline becoming ovate toward the top of the stem, rounded at base, often with a few salient teeth; stems 1-4 dm, simple or branched above; pet white, 3-5 mm; frs crowded and closely ascending on short pedicels, oblong, elliptic, or lanceolate, glabrous to stellate, 5-10 mm, acute; persistent style 0.1-0.3 mm; 2n=32. Various habitats; Greenl. to Hudson Bay and N.B.; Isle Royale, Mich., n. Eurasia.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.