Cypripedium californicum, the California Lady's Slipper, has the smallest range of the western lady's slippers- limited to southwestern Oregon and northern California. Often found in large colonies, the tall plants may exceed 120 cm with alternating leaves and numerous flowers. The flowers have yellow petals and a white pouch similar in size to C. passerinum, but the number of flowers and their display along the stem, distinguishes this orchid from all other lady's slippers. This orchid prefers wet areas such as seeps, marshes, forest openings and steep slopes, usually with a serpentine substrate.

Cypripedium californicum is considered vulnerable because of its limited distribution and its occurrence in areas that could be logged or mined. This orchid is also threatened by illegal collection.

This orchid is pollinated by the carpenter bee, Ceratina acantha and may become territorial when other insects approached the flower.