Columbia Lady's Slipper (Cypripedium x columbianum)

As the "x" in the scientific name indicates, this is a natural hybrid, in this case of the Mountain Lady's Slipper, Cypripedium montanum, which it resembles, and the Yellow Lady's Slipper, Cypripedium parviflorum.  It is, in my opinion less beautiful than either of its parents.

In flower size and color, it it is intermediate between the two parents especially in the color of the pouch which ranges from off-white to pale yellow, and in the location where we found it was part of a mixed population that included both parents.

The difference between it and the Mountain Lady's Slipper is in the color of the sepals and petals which tend toward a yellowish-green, and the shape and sometimes the color of the pouch which tends to be shaped more like the pouch of the Yellow Lady's Slipper and can vary from white to yellowish (the yellowish color of the petals and sepals and a yellow tint to the pouch can be clearly seen in the last photo).

The parents are the two species pictured below: