1. Wilhelmsia physodes (Fischer ex Seringe) McNeill, Taxon. 9: 110. 1960.
Arenaria physodes Fischer ex Seringe in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 1: 413. 1824; Merckia physodes (Fischer ex Seringe) Fischer ex Chamisso & Schlechtendal
Rhizomes spreading. Stems slen-der, 2-10(-20) cm, pubescent with spreading, purplish, jointed, weakly glandular-tipped hairs. Leaf blades 2-8 × 5-15 mm, sparsely pubescent with purplish, jointed hairs, becoming glabrate on faces, ciliate on margins and midrib. Pedicels 5-25 mm, pubescent. Flowers: sepals often purple tinged, oblong-ovate, 2-2.5 × 4.5-6 mm, apex acute to short-acuminate, sparsely pubescent; petals narrowly oblanceolate, abruptly constricted towards base, 5-6 mm; stamens moderately exserted, 2-3 mm. Capsules purplish, globose or slightly depressed, 7-10 mm diam., glabrous. Seeds 1.2-1.5 mm. 2n = 50-60, 66, 70 (Siberia), 72 (Siberia), 100-110.
Flowering summer (late Jun-Aug). In sand or mud along streams and on gravel bars; 0-1500 m; N.W.T., Yukon; Alaska; Asia (Russian Far East, Siberia).