Only one petal forms the shoe. The shoe is NOT made of several petals fusing together. The single lip petal (labellum) folds and inflates. American botanists do NOT regard the small-yellow lady's slipper as a separate species. We do recognize 3 VARIETIES of the same yellow species of Cypripedium parviflorum. Check out the appropriate volume of Flora of North America. Cypripedium kentuckiense resembles C. parviflorum but IS now considered a separate species and has a much larger-rounder shoe. Yes, orchids do produce some of the most complicated examples of f flower architecture and pollen dispersal but that does NOT make them the most highly evolved plants.