''Cypripedium candidum'', known as the small white lady's slipper or white lady's slipper, is a rare orchid of the genus '' Cypripedium''. It is native to eastern North America across the northern United States and southern Canada.

Distribution

''Cypripedium candidum'' is found from western

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, across southern Ontario to North Dakota, and south to New Jersey and Missouri. There are isolated populations of ''Cypripedium candidum'' in Connecticut, Maryland, Manitoba,Brownell, V.R. 1981. COSEWIC status report on the small white Lady’s-slipper Cypripedium candidum in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 63 pp. Virginia, Alabama, and (formerly) Saskatchewan. It is found in alkaline wetland and fens, often fragmentedEnvironment Canada. 2014. Recovery Strategy for the Small White Lady’s-slipper (Cypripedium candidum) in Canada roposed Species at Risk Act Recovery Strategy Series. Environment Canada, Ottawa. v + 30 pp. in rich, highly calcareous soils, sedge meadow edges, and calcareous ditches.

Description

''Cypripedium candidum'' grows to a height of and is one of the smallest species of North American ''Cypripedium''. It blooms from late May to early June. Its white pouch-like lip, sometimes dotted with maroon on the inside, is accented by tan, green or brown lateral sepals and petals. It has been known to hybridize with the small yellow ladyslipper, ''C. parviflorum'' var. ''makasin'', resulting in the natural hybrid ''Cypripedium'' × ''andrewsii''. The leaves and stems are slightly pubescent. The plants grow in (generally) long-lived clumps, with some clumps having up to 50 or more flowers. It is a perennial, with horizontal, wiry-rooted rhizomes growing a few centimeters below the surface of the soil, and hence resistant to most prairie fires.

Conservation

''Cypripedium candidum'' is considered rare across Canada, endangered in Ontario, and protected under the Ontario Endangered Species Act. It is believed to be extirpated from Saskatchewan. In Ontario, this orchid has never been common due to limited occurrences of fens in its southern Ontario range. It is now known from only two sites in Ontario. It is threatened in the United States, extirpated from Pennsylvania, endangered in South Dakota and Wisconsin, Kentucky, and Michigan, and rare in Missouri and North Dakota. In Illinois, it was listed as endangered in 1980, downgraded to threatened in 1998, and delisted in 2014, when the

Illinois Endangered Species Protection Board The Illinois List of Endangered and Threatened Species is reviewed about every five years by the Illinois Endangered Species Protection Board (ESPB). To date it has evaluated only plants and animals of the US state of Illinois, not fungi, algae, or ...

considered it to be "recovered and/or more common than originally thought". It is listed in Canada as N2, or endangered. Globally, however, it is listed as G4 (apparently secure) because there are protected sites across its entire range. Habitat loss due to fragmentation through agriculture and development, suppression of fire, incursions by invasive species, especially reed canary grass ('' Phalaris arundinacea''), dogwood ('' Cornus'' sp.), leafy spurge (''

Euphorbia esula ''Euphorbia esula'', commonly known as green spurge or leafy spurge, is a species of spurge native to central and southern Europe (north to England, the Netherlands, and Germany), and eastward through most of Asia north of the Himalaya to Korea a ...

''), St. John's wort ('' Hypericum'' spp.), and buckthorn ('' Rhamnus'' spp.), changes in hydrology, loss of pollinators, hybridization and environmental challenges to the obligate mycorrhizae that support this species are all responsible for its decline. It also has a low seed set caused by often unpollinated flowers. Pollinators for this flower include andrenid and halictid bees. They are observed entering the lip of the flower from the opening to deposit pollen on the stigma while simultaneously brushing the anther to pick up more pollen.Catling, P.M., & Knerer, G. (1980). Pollination of the small white lady's-slipper (Cypripedium candidum) in Lambton County, Southern Ontario. Like many wild orchids, this species has been further endangered by collecting for generally futile attempts at cultivation. It is shade-intolerant and therefore requires substantial management for invasive and woody species as part of any species recovery strategies. Long-term monitoring of this species is being done through various scientific organizations, including the Chicago Botanic Garden's

Plants of Concern Plants are predominantly Photosynthesis, photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all curr ...

program. Woody encroachment is considered the greatest modern threat to monitored small white lady's slipper populations in the Chicago region. The Plants of Concern program found significantly more lady's slipper plants when prescribed burning and brush removal were conducted compared to sites without the employment of these management tools.

References

External links

* {{Taxonbar, from=Q1817011 candidum Orchids of Canada Orchids of the United States Orchids of Maryland Flora of the Great Lakes region (North America) Flora of the Northeastern United States Flora of the North-Central United States Flora of the Southeastern United States Flora of the Appalachian Mountains Flora of Ontario Flora of Manitoba Flora of Saskatchewan Flora of Virginia Plants described in 1805