5. Physaria arctica (Wormskjöld ex Hornemann) O’Kane & Al-Shehbaz, Novon. 12: 321. 2002.
Alyssum arcticum Wormskjöld ex Hornemann in G. C. Oeder et al., Fl. Dan. 9(26): 3, plate 1520. 1816; Lesquerella arctica (Wormskjöld ex Hornemann) S. Watson; L. arctica subsp. purshii (S.Watson) A. E. Porsild; Vesicaria arctica (Wormskjöld ex Hornemann) Richardson; V. leiocarpa (Trautvetter) N. Busch
Perennials; caudex simple or branched, (woody, cespitose); ± densely pubescent, trichomes (sessile or short-stalked), several-rayed, rays distinct, furcate or bifurcate, (somewhat umbonate, finely tuberculate to ± smooth). Stems simple or few to several from base, erect to spreading or prostrate, 0.5-2(-3) dm. Basal leaves (usually ± rosulate); blade obovate to oblanceolate, (1-)2-6(-15) cm, margins entire. Cauline leaves (sessile or shortly petiolate); blade oblanceolate or lingulate, 0.5-1.5(-3) cm, margins entire. Racemes loose. Fruiting pedicels (erect to divaricate or ascending), (5-)10-20(-40) mm, (stout). Flowers: sepals ovate to elliptic, (3-)4-5(-6) mm, (median pair often thickened apically, cucullate); petals spatulate, 5-6(-7) mm, (blade gradually narrowed to claw). Fruits subglobose to ellipsoid, uncompressed, 4-6(-9) mm; valves (not retaining seeds after dehiscence), glabrous or sparsely pubescent outside, trichomes sessile; replum as wide as or wider than fruit; ovules (8-)10-14(-16) per ovary; style 1-2.5(-4) mm. Seeds plump. 2n = 60.
Flowering May-Aug. Typically on sand and gravel from calcareous bedrock, river bars and terraces, cliff ledges, scree and talus slopes, often growing after disturbance; 0-1800 m; Greenland; Alta., B.C., Man., Nfld. and Labr., N.W.T., Nunavut, Que., Yukon; Alaska; circumarctic (except n Europe, ne Russia).