Cypripedium acaule, the Pink Lady Slipper orchid is a hardy ground orchid native to the U.S. and Canada. Slipper orchids in bloom in woodlands and marshes each spring.
The flower is a bulbous pouch which appears beneath 2 or 3 dog-ear-shaped brown sepals. The pink pouch of C. acaule differs from those of other Cypripedium species in that it opens through a slit down the center rather than a round hole at the top.
The showy blooms occur singly on long stalks which emerge from a set of bright green leaves. The pouch flowers vary in hue from white in C. acaule alba to pinkish purple.
They contain the plant's reproductive parts and cutting them can hinder regeneration of native colonies.
This Cypripedium species needs acidic, well drained soil that is moist and rich in humus but not fertile. It relies on a particular type of mycorrhizae (fungus) to grow and this fungus can only survive in acidic, infertile soil. The kind of soil that most other garden plants like will not support it.
If you have a colony of Slipper orchids on your property and you wish to propagate them, dig a clump up and transfer it along with some of the soil from the original planting area to the new location. This will insure that the necessary mycorrhizae are present.
Perform this operation in early spring just as growth begins or in midsummer after the flowers fade.
Plant the Lady Slipper orchid in part shade. It is hardy in zones 3-7.
This plant is endangered in Illinois and Tennessee.