Hybrid Lady's Slipper. This is a hybrid of the two previous species, Small White and Small Yellow Lady's Slipper. Depending on your treatment of the large and small yellows (as varieties or distinct species), this hybrid is either Cypripedium X andrewsii or Cypripedium X favillianum (see Swink and Wilhelm, 1994). This orchid is known to backcross with parents, resulting in a "hybrid swarm."
"Every creature is better alive than dead, men and moose and pine trees, and he who understands it aright will rather preserve life than destroy it." Henry David Thoreau, The Maine Woods