Lady Slippers (aka Lady's Slipper, Lady's-slipper, Ladyslipper) is a term used to describe the orchids in the subfamily Cypripedioidea, which includes the genera Cypripedium, Mexipedium, Paphiopedilum, Phragmipedium and Selenipedium, distinguished by their slipper-shaped pouches (modified labellums), which function by trapping insects so that they are forced to climb up past the staminode, behind which they collect or deposit pollinia.
This subfamily has been considered by some (Rasmussen, 1985) to be a family Cypripediaceae, separate from the Orchidaceae.
The subfamily Cypripedioideae is monophyletic and consists of five genera. Their common features are two fertile diandrous (that is, with two perfect stamens) anthers, a shield-shaped staminode and a saccate (sac-shaped) lip.
Cypripedium are found across much of North America, as well as in parts of Europe. The state flower of Minnesota is the Showy Lady's Slipper (Cypripedium reginae). The Pink Lady's Slipper, (Cypripedium acaule), is the official state wildflower of New Hampshire. The Lady's Slipper is also the official provincial flower of Prince Edward Island, a province of Canada.
Paphiopedilums are found in the tropical forests of southeast Asia reaching as far north as southern China. Paphiopedilum is quite easy to cultivate and therefore is popular among orchid enthusiasts. In fact, overcollecting of this genus has caused some problems in its original habitat.