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White Lady’s Slipper

Saving the White Lady’s Slipper 

(Cypripedium candidum) or the White Lady’s Slipper is a type of flowering plant that belongs to the Orchid family, which is one of the larger flowering plant families in the world. Orchids are characterized by having vibrant and intricate flowers that often have a pleasant fragrance associated with the bloom. The White Lady’s Slipper is a food deceptive flower, meaning the flower advertises a food (nectar) reward to pollinators while not providing one. This unique floral adaptation reduces the likelihood of self-pollination and dramatically decreases the rate of pollination.

These flowers naturally occur from western New York, across southern Ontario to North Dakota and south to New Jersey and Missouri. They occur in prairie fen areas with high pH. In Ohio, the White Lady’ Slipper is limited to three disjunct populations, two of which are at considerable risk of becoming extirpated because of declines in native prairie habitat due to agriculture and urbanization. These factors have resulted in the species being listed as endangered in the state of Ohio.

The Toledo Zoo is working on a plan to prevent the extinction of this flower by conducting research in situ (natural habitat) and ex situ (in a lab) with the eventual goal of reintroducing additional orchid plants into their native habitat.

The in situ research composes of developing an understanding of the distribution of the species which seems to be limited by a suite of biotic and abiotic characteristics which are needed by the species to survive. This part of the research plan focuses on what variables (soil pH, temperature, surrounding vegetation, precipitation, etc.) are important to the presence and successful reproduction of the species. By understanding these important characteristics, we will be able to create mathematical models which will allow us to select reintroduction sites that have the highest probability of success.


The ex situ research focuses on White Lady’s Slipper reproduction which is very complex. Orchid seeds are unique in that they lack endosperm (food that provides energy for the seed to germinate). The lack of endosperm allows the seed to be very light and disperse well in the wind, however, this results in complex germination requirements.  Orchid seeds in the wild must become infected with a mycorrhizal fungi which provides the carbon and nutrients to begin germination. Using what we learn in the field regarding these fungal interactions, the Toledo Zoo in the process of developing a captive rearing and seed germination program in a sterile lab to produce plants that will one day be planted in the areas identified by the distribution model. The Zoo is also studying how we can encourage the interactions of the seeds and the fungi in restoration areas to increase reproduction rates in the wild.

Researchers and volunteers collect valuable environmental data in the habitat of the white lady’s slipper including soil pH, soil type, temperature, precipitation and surrounding vegetation.

Dr. Ryan Walsh (right) discusses the environmental needs and natural history of the white lady’s slipper to a group of volunteer researchers.

The white lady’s slipper gets it’s name from the floral lip which is enlarged and usually bright white, although can have faint purple veins or spots. The plant typically grows to a height of 10-35 cm (3.9-13.8 in.).

The white lady’s slipper

White lady’s slipper habitat.