White Lady Slipper Orchid (Cypripedium candidum)
By Christopher David Benda
The white lady slipper is a showy species in the Orchid family (Orchidaceae). In fact, the name “Cypripedium” translates to “Venus slipper” and refers to the shape of the flowers. The specific epithet “candidum” means “white,” also referring to the flowers.
These orchids have a pouch shaped labellum that resembles a slipper. Three sepals spread laterally and vertically around the labellum. The flowers are bisexual and deceptive, perhaps because they must be. The flower parts are arranged so that they cannot self-fertilize, and thus animal pollinators are required. The showy flowers lure in insect pollinators (mainly bees), where they get trapped in the pouch. While they search for the one-way exit out a slit in the back of the labellum, they get covered in pollen with the hope they will be fooled again, and fly into another lady slipper flower, resulting in fertilization.
Also inhabiting the pouch are pollinator predators, particularly crab spiders that lie in wait for unsuspecting smaller flying insects to enter where they attack and consume them.
The seeds dust-like and wind dispersed. Thousands of seeds are released once the capsules are desiccated and split open. Only few germinate and survive, because they are dependent on mycorrhizal fungi, which act as root hairs, to acquire nutrients. Plants are slow growing and exceptionally long lived.
Orchids long sought after and often over collected. The plants can fight back to some degree, as they contain a chemical defense called cypripedium, a resinoid which is a volatile oil that causes a rash. These orchids are also heavily collected for medicinal uses as a sedative.
White lady slipper orchids prefer open and wet places like wet prairies and fens. Its range is centered in the upper Midwest where it is considered rare.
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