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Cypripedium acaule
Also called Mocassin Flower, Moccasin Flower, Pink Lady's Slipper Orchid, Pink Moccasin Flower, Lady's Slipper Orchid, Pink Ladyslipper, Small Pink Lady's Slipper
A wild North American orchid with a single pink, slipper-shaped flower, native to eastern Canada and the eastern United States. It is very hard to grow in gardens because it needs very acidic soil and a specific fungal partner, so most plants should be left in the wild.
Cypripedium acaule, the pink lady's slipper or moccasin flower, is a species of flowering plant in the orchid family Orchidaceae native to eastern North America. It is currently the provincial flower of Prince Edward Island, Canada, and the state wildflower of New Hampshire, United States.
Indigenous peoples traditionally used this plant for medicinal purposes. For example, Algonquin people, who form part of the larger cultural group known as the Anishinaabeg, traditionally used C. acaule to treat menstrual disorders. Due to population decline, harvesting for medicinal purposes is no longer recommended. As C. acaule takes many years to go from seed to mature plant, the gathering of seed-bearing specimens is presently unsustainable.
Seed germination labs have increased the commercial availability of C. acaule, although it still tends to be less commonly available than other Cypripedium species and hybrids. This is primarily due to the extra care that must be provided if the growing site is not naturally suitable for in-ground cultivation. This plant grows in soils below a pH of 5, often at 4–4.5. At this high acidity soil fungus is suppressed, and C. acaule can thrive. There is even evidence that it is partially myco-heterotrophic, parasitizing fungus that attempts to invade its roots. However, in soils above pH 5, soil microbes become more than C. acaule can manage, and the plants rot. Although, C. acaule is photosynthetic, it still relies on specific fungal partners for nutrient exchange. These fungi colonize the orchid roots and form structures called pelotons, which allows for nutrient transfer.
Seedlings germinated in a sterile environment can grow and thrive in a much higher pH than 5, but must be grown below 5 if removed from the sterility.
Cypripedium acaule can be found in the eastern third of the United States, particularly in the Great Lakes region and the Northeast in New Hampshire and Maine, south along the Appalachians to Alabama. It is widespread in Canada, where it is found in every province except British Columbia. It also occurs in the Northwest Territories and in Saint Pierre and Miquelon. Within its geographic range, it can be found in a wide variety of environments, from coastal plains, to pine barrens, to mountaintops.
Ram's head lady's slipper · Lady's-slipper orchid · California lady's slipper · White lady's-slipper · Dickinson's lady's slipper · Elegant Cypripedium · Clustered lady's slipper · Yellow Cypripedium · Formosa's lady's slipper · Franchet's Cypripedium · Spotted lady's slipper · Henry's Cypripedium
Text excerpted from the Wikipedia article Cypripedium acaule by its contributors, under CC BY-SA 4.0; the excerpts and the care summary drawn from them are shared under the same licence.
The care summary was written by AI (Claude, Anthropic) from the sources on this page, with general growing knowledge where they are silent. Check before relying on it.
Life form, climate and native range: World Checklist of Vascular Plants, Royal Botanic Gardens, Kew (CC BY 3.0), reformatted; see Plants of the World Online.
