See Taxonomy of the orchid family.

Lady Slippers is a term used to describe a variety of orchids in the subfamily Cypripedioidea, which includes the genera Paphiopedilum, Phragmipedium, Selenipedium , Cypripedium and the monotypic Mexipedium, 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, 185) to be a family Cypripediaceae, separate from the Orchidaceae.

The subfamily Cypripedioideae is a monophyletic clade and consists of five genera. Their common features are : two fertile diandrous (= with two perfect stamens) anthers, a shield-shaped staminode and a saccate (sac-shaped) lip.

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.

Phragmipedium, found across northern South and Central America, is also easy to cultivate as it requires lower temperatures than Paphiopedilum, eliminating the need for a greenhouse in many areas.

Cypripedium are found across much of North America, as well as in parts of Europe. The state flower of Minnesota, a state in the United States, is the Showy Lady's Slipper (Cypripedium reginae).