Plants erect, 25-71 cm. Leaves 4-6, inserted toward base or scattered along stem, alternate, erect, ascending, or spreading; blade suborbiculate or broadly ovate to elliptic-lanceolate, 3.3-17 × 2.5-9.5 cm. Flowers 1-3; sepals greenish, suffused, often heavily, with reddish brown or madder, or rarely clear green; dorsal sepal lance-acuminate to elliptic-lance-acuminate, 33-60 × 8-16 mm; lateral sepals connate; synsepal 30-60 × 6-18 mm; petals spreading-deflexed, same color as sepals, spirally twisted, linear to linear-lanceolate, 36-77 × 3-5 mm; lip white, rarely suffused with magenta, obovoid or oblance-ovoid to oblance-fusiform, 19-33 mm; orifice basal, 13-22 mm; staminode lanceoloid to broadly ovoid or ellipsoid-ovoid.

Flowering Feb--Sep. Mesic to dry (rarely wet) coniferous, deciduous, and broadleaf evergreen forests, openings, and thickets, around shrubs on open slopes; 0--2400 m; Alta., B.C.; Alaska, Calif., Idaho, Mont., Oreg., Wash., Wyo.

Plants of Cypripedium montanum grown in exposed, relatively sunny situations have the ascending leaves inserted along the basal portion of the stem and the flowers displayed well above the leaves. In shadier, especially sheltered sites, the spreading leaves may be more evenly scattered along the stem. In this species the apical margin of the orifice of the lip is usually acute, in common with C. candidum, and in contrast to the usually obtuse margin in C. parviflorum; this difference can aid determination of discolored herbarium specimens. Hybrids of C. montanum and C. parviflorum have been designated C. × columbianum Sheviak. See 11. C. parviflorum for a general discussion of hybridization and variation within and between related species.