Perennials; (cespitose); caudex branched (sometimes with persistent leaf remains); often scapose. Stems branched or unbranched, (0.2-)0.4-1.4(-2) dm, pubescent throughout, trichomes simple and 2-4-rayed, 0.2-0.5 mm. Basal leaves rosulate; petiolate; petiole (0-0.5 cm), ciliate throughout; blade oblanceolate to narrowly obovate or narrowly lanceolate, 0.4-2.1 cm × 1.5-7 mm, margins with 1-3 teeth on each side, (ciliate, trichomes simple and 2-rayed, 0.2-0.8 mm), surfaces pubescent abaxially with stalked, (2-)4(-6)-rayed trichomes, 0.1-0.4 mm, adaxially glabrous or pubescent, with simple and stalked, 2-rayed trichomes, 0.1-0.5 mm. Cauline leaves 0-3(-5); sessile; blade ovate to oblong, margins often dentate, (ciliate). Racemes 5-23-flowered, ebracteate or proximalmost 1(-3) flowers bracteate, considerably elongated in fruit; rachis slightly or not flexuous, pubescent as stem. Fruiting pedicels suberect to ascending (often appressed to rachis), straight, (1.5-)2.5-5(-9) mm, pubescent, trichomes simple and 2-4-rayed. Flowers: sepals ovate, 1.7-2.5 mm, pubescent, (trichomes simple and short-stalked, 2-4-rayed); petals white, spatulate, 2.5-4 × 1.7-2.5 mm; anthers ovate, 0.3-0.4 mm. Fruits (sometimes subappressed to rachis), oblong to lanceolate-elliptic, plane, flattened, 4-8 × 2-3 mm; valves glabrous or pubescent, trichomes simple and short-stalked, 2-rayed, 0.05-0.25 mm; ovules 18-26 per ovary; style (0.01-)0.1-0.4(-0.5) mm, (glabrous, stigma about as wide as style). Seeds oblong, 0.9-1.2 × 0.5-0.7 mm. 2n = 48.
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Perennial; basal lvs oblanceolate to obovate, 1–2 cm; cauline lvs 1–5, ovate, 5–10 mm, rounded at base, the upper often subtending a fl; stems 1–2 dm; mature racemes dense, forming a third to half the total height of the pl; pedicels and frs ascending; pet white; frs oblong, elliptic, or lance-oblong, mostly 7–9 × 2.2–3.2 mm, veiny, glabrous or seldom sparingly stellate-puberulent; persistent style 0.1–0.3 mm, or virtually obsolete; 2n=48. Rocky ledges and cliffs; e. and ne. Can. and adj. U.S.; n. Europe; known in our range only from Cape Breton Isl. and Cook Co., Minn.