Arabidopsis arenicola

Perennials; (caudex usually branched, rarely simple, with persistent petiolar remains); glabrous throughout or sparsely to moderately pubescent, trichomes simple and short-stalked, forked, (to 0.5 mm). Stems often several from base (caudex), erect, ascending, or decumbent, unbranched or branched (few) distally, 0.5-2(-3) dm, glabrous or sparsely pubescent distally. Basal leaves: petiole 0.5-2 cm, (ciliate or glabrous); blade (fleshy), oblanceolate to spatulate, 0.5-2 cm × 2-6 mm, margins entire or dentate, (not ciliate), apex obtuse or acute, surfaces pubescent or glabrous. Cauline leaves [(1-)2-4(-6)] sessile; blade oblong to oblanceolate, 0.7-1.8(-2.5) cm × 2-5 mm, (base not auriculate), margins usually entire, rarely dentate, (apex obtuse or acute, surfaces glabrous or sparsely pubescent). Fruiting pedicels ascending to divaricate, 5-10(-12) mm, (glabrous). Flowers: sepals 1.7-3 mm, lateral pair not saccate basally; petals white, usually oblanceolate, rarely spatulate, 4-5 × 1-2 mm; filaments 1.7-3 mm. Fruits (suberect to divaricate), straight, smooth, terete or slightly flattened, (0.8-)1-2(-2.8) cm × 1.5-2.2(-2.5) mm; valves each with obscure midvein; ovules 30-54 per ovary; style 0.4-0.8 mm. Seeds (sometimes sub-biseriate), reddish brown, narrowly oblong, 0.9-1.1 mm, pointed distally; cotyledons incumbent. 2n = 32.

Flowering Jun-Aug. Sandy beaches, gravel, flats of streambeds; 0-1500 m; Greenland; Man., Nfld. and Labr. (Labr.), Nunavut, Ont., Que., Sask.