The yellow lady's slipper or yellow lady's slipper (Cypripedium calceolus) is also called reddish-brown lady's slipper, Marian lady's slipper (the flower of the yellow lady's slipper is mentioned in legends associated with the Virgin Mary), European lady's slipper, or more commonly just lady's slipper. The shape of the flower also led to the name "Kriemhild's helmet" or "Krimhild's helmet". The yellow lady's slipper is one of the most magnificent wild orchid species in Europe and is protected in all countries according to the Habitats Directive Appendix II. It belongs to the genus of lady's slippers (Cypripedium) in the orchid family (Orchidaceae) and is the type species of this genus.
In order to draw attention to the particular endangerment and protection of this species, the Yellow Lady's Slipper was voted Orchid of the Year by the Working Group on Native Orchids in 1996 and 2010.