Plants scapose; sparsely pubescent, trichomes simple and 2-forked. Stems simple or few to several from base, erect, (unbranched), 0.3-1.1(-1.5) dm. Basal leaves: blade narrowly spatulate to oblanceolate, (0.5-)1-3(-5) cm × 1-3.5 mm, base (membranous), broadly expanded near point of attachment, margins entire, (sparsely ciliate proximally), apex obtuse. Cauline leaves: 0 or 1 (or a leaflike bract subtending proximalmost pedicel). Fruiting pedicels erect or ascending, (1.2-)1.5-4.5(-4.9) mm. Flowers: sepals 2-3(-3.5) × (1.1-)1.2-1.7 mm; petals white (or claw purplish), (3-)3.3-4.8(-5) × (1.2-)1.4-2.5(-3) mm, (claw and blade usually well-differentiated, apex rounded); filaments 1.7-2 mm; anthers oblong, 0.3-0.4 mm. Fruits lanceoloid-subulate, not torulose, (straight), (0.3-)0.4-0.8(-1) cm × (0.7-)1-1.5(-1.7) mm; valves glabrous or, sometimes, sparsely pubescent; septum margin broadly expanded basally (forming sacklike pouch around proximalmost seed in each locule); ovules 10-16 per ovary; style 0.5-1(-1.2) mm; stigma 2-lobed or entire. Seeds somewhat uniseriate, oblong, 1-1.4 × 0.5-0.9(-1) mm. 2n = 56. Flowering Jun-Jul. Limestone barrens; of conservation concern; 0-60 m; Nfld. and Labr. (Nfld.).