Clustered Lady's Slipper: Cypripedium fasciculatum - Leaves generally 2, almost opposite. The 2-4 flowers are clustered and greenish-yellow to purplish tinged.
Mountain Lady Slipper, Mountain Lady's Slipper: Cypripedium montanum - The several leaves are alternately arranged on the stem. The 1-3 flowers are are more spread out. The lip is white to purplish tinged without purplish dots.
Fairy Slipper, Greater Yellow lady's Slipper, Lesser Yellow Lady's Slipper Orchid, Yellow Lady's-slipper: Cypripedium parviflorum (Synonyms: Cypripedium calceolus var. parviflorum, Cypripedium parviflorum var. makasin, Cypripedium parviflorum var. parviflorum, Cypripedium parviflorum var. pubescens) - The several leaves are alternately arranged on the stem. The 1-3 flowers are are more spread out. The lip isyellow with purplish dots around the opening to the bowl.