Cypripedium calceolus var. pubescens
Native to Minnesota. Perennial to 23" tall. One to several stems in a clump. Leaves 2 to 6 per stem, ovate, 3"-8" long. One to two flowers per stem; flowers with conspicuous yellow inflated pouch (or lady's slipper); blooms in May-June. Found most often in mesic (moderate moisture) hardwoods and conifer swamps, occasionally in roadside ditches.