Cypripedium passerinum

Plants erect, 12-38[-50] cm. Leaves 3-7, along length of stem, alternate, ascending to spreading; blade elliptic to elliptic-lanceolate or ovate-lanceolate, 5-19 × 1.5-6 cm. Flowers 1(-2); sepals white or green; dorsal sepal suborbiculate to obovate-orbiculate, rarely elliptic, 11-20 × (7-)9-15 mm; lateral sepals connate to nearly distinct, 6-12 mm, segments 3-6 mm wide; synsepal 6-15 mm wide; petals spreading, white, oblong to linear-elliptic, flat, 12-20 × 3-6 mm; lip white, rarely pinkish, obovoid, 11-20 mm; orifice basal but often proportionally very large, 9-13 mm; staminode cordiform-ovoid to ovoid-oblong. 2n = 20.

Flowering Jun--Jul. Moist coniferous forests, thickets, openings, tundra, especially in coarse soils of terraces and stream banks; 0--2200 m; Alta., B.C., Man., N.W.T., Nunavut, Ont., Que., Sask., Yukon; Alaska, Mont.