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Yellow Lady’s Slipper Notecard



Yellow Lady’s Slipper (Cypripedium calceolus) and Mining Bee (Andrena spp.)

The Yellow Lady’s Slipper is found flowering in bogs, swamps and rich woods from May to July. It occurs from Quebec and Vancouver south to Missouri and Georgia. This striking flower is also called “Whippoorwill’s Shoe” and its Latin name “calculus” means “a little shoe”, which the flower does indeed resemble.

The flower’s yellow color and attractive fragrance lures small bees, particularly mining bees, which nest in meadows and meadows and forest edges throughout North America. Female mining bees dig long branching tunnels in the soil; they lay their eggs in brood cells, which they provision with pollen balls.

Mining bees which visit the Yellow Lady’s Slipper unwittingly perform a valuable pollination service for this member of the highly evolved orchid family, which has evolved intricate measures to assure cross-pollination. Lines converge toward the circular opening on the upper surface of the inflated pouch-like flower. Following these lines, the bee enters the flower easily, but as the bee readies to leave, she finds that the entryway has closed behind her. Instead, a thin-walled transparent area of the flower provides a window of light which attracts the bee to a small exit. As the bee squeezes through the exit she brushes under the female stigma and then the male anther, which plasters her with pollen as a parting gift. When she repeats this scenario in the next flower, the female stigma scrapes pollen off her back, thus effecting cross-pollination. The male anthers then apply a fresh plastering of pollen to her back, repeating the cycle, flower after flower.

artwork and text by Lynn Usack © 1996