Yellow lady's slipper (Cypripedium calceolus)

Yellow lady's slipper photograph;  MN DNR, Welby Smith

Two varieties of Yellow Lady-slippers in 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); bloom in May-June. Found most often in mesic (moderate moisture) hardwoods and conifer swamps, occasionally in roadside ditches.