Calypso bulbosa - (L.) Oakes
Fairy Slipper
Other English Common Names: Calypso, Venus' Slipper
Other Common Names: fairy slipper
Taxonomic Status: Accepted
Related ITIS Name(s): Calypso bulbosa (L.) Oakes (TSN 43508)
French Common Names: calypso bulbeux
Unique Identifier: ELEMENT_GLOBAL.2.132752
Element Code: PMORC0D010
Informal Taxonomy: Plants, Vascular - Flowering Plants - Orchid Family
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Monocotyledoneae Orchidales Orchidaceae Calypso
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Concept Reference
Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Calypso bulbosa
Taxonomic Comments: Distinct species; var. americana is very similar to var. occidentalis.
Conservation Status

NatureServe Status

Global Status: G5
Global Status Last Reviewed: 16May2016
Global Status Last Changed: 22Jun1990
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G5 - Secure
Reasons: Plant widely distributed but local. Listed as nationally rare in USA by Crow (1982). Range is circumboreal; Labrador to Alaska, south to Maine, Michigan, New York, west into the Rockies, Arizona and California, also in Europe. Most often found in cool, mature cedar swamps or on slopes of mixed coniferous growth underlain by some type of calcareous bedrock. May be vulnerable to local reduction due to herbivory from overly abundant deer.
Nation: United States
National Status: NNR
Nation: Canada
National Status: N5 (29Feb2012)

U.S. & Canada State/Province Status
United States Alaska (S4), Arizona (S3), California (SNR), Colorado (S4?), Idaho (SNR), Maine (S3S4), Michigan (S2), Minnesota (SNR), Montana (S4), Navajo Nation (S1), New Hampshire (SNR), New Mexico (SNR), New York (SH), Oregon (SNR), South Dakota (S3), Utah (S4), Vermont (S1), Washington (SNR), Wisconsin (S2), Wyoming (S3)
Canada Alberta (S5), British Columbia (SNR), Manitoba (S4), New Brunswick (S2), Newfoundland Island (S1), Northwest Territories (SNR), Nunavut (S2), Ontario (S4), Quebec (S2), Saskatchewan (S3), Yukon Territory (S3S4)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent Comments: Circumboreal species; Labrador to Alaska, south to Maine, Michigan, New York, west into the Rockies, Arizona and California, also in Europe.

Number of Occurrences: 81 to >300
Number of Occurrences Comments: More than a hundred occurrences seen in Michigan alone.

Overall Threat Impact Comments:

In general, harvesting of timber and therefore loss of habitat is the worst threat. Collecting is a threat wherever populations are known and accessible. Another potential factor is loss of canopy due to insect infestations and/or disease. Frost damage to the tubers may occur during some winters. Also, as noted by Judziewicz (2001), the species is vulnerable to reduction from herbivory by locally overabundant deer.

Intrinsic Vulnerability Comments: Apparently intolerant of soil temperatures in excess of 15 C and of canopy cover less than 60% (Caljouw 1981).

Other NatureServe Conservation Status Information

Global Range: Circumboreal species; Labrador to Alaska, south to Maine, Michigan, New York, west into the Rockies, Arizona and California, also in Europe.

U.S. States and Canadian Provinces
Color legend for Distribution Map

U.S. & Canada State/Province Distribution
United States AK, AZ, CA, CO, ID, ME, MI, MN, MT, NH, NM, NN, NY, OR, SD, UT, VT, WA, WI, WY
Canada AB, BC, MB, NB, NF, NT, NU, ON, QC, SK, YT

Range Map
No map available.

U.S. Distribution by County Help
State County Name (FIPS Code)
AK Prince of Wales-Outer Ketchikan (CA) (02201)*, Sitka (02220), Wrangell-Petersburg (CA) (02280)*
AZ Apache (04001), Coconino (04005), Greenlee (04011)
MI Alger (26003), Antrim (26009)*, Benzie (26019)*, Cheboygan (26031)*, Chippewa (26033), Crawford (26039)*, Delta (26041), Emmet (26047)*, Gogebic (26053)*, Iron (26071), Isabella (26073)*, Keweenaw (26083), Mackinac (26097), Marquette (26103)*, Menominee (26109), Montmorency (26119)*, Presque Isle (26141), Roscommon (26143)*, Schoolcraft (26153)
NH Coos (33007)*, Grafton (33009)*
NY Clinton (36019)*, Genesee (36037)*, Herkimer (36043)*, Lewis (36049)*, Onondaga (36067)*, Otsego (36077)*, St. Lawrence (36089)*
SD Custer (46033), Lawrence (46081), Pennington (46103)
VT Addison (50001)*, Caledonia (50005), Orleans (50019), Rutland (50021)*
WI Ashland (55003), Bayfield (55007)*, Burnett (55013)*, Door (55029)*, Douglas (55031), Florence (55037), Forest (55041), Iron (55051)*, Langlade (55067), Oconto (55083), Oneida (55085), Price (55099), Sawyer (55113), Vilas (55125)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
01 Upper Connecticut (01080101)+*, Passumpsic (01080102)+, Waits (01080103)+
02 Mohawk (02020004)+*, Upper Susquehanna (02050101)+*
04 St. Louis (04010201)+*, Beartrap-Nemadji (04010301)+, Bad-Montreal (04010302)+*, Black-Presque Isle (04020101)+, Ontonagon (04020102)+*, Keweenaw Peninsula (04020103)+, Dead-Kelsey (04020105)+*, Betsy-Chocolay (04020201)+, Waiska (04020203)+, Door-Kewaunee (04030102)+*, Peshtigo (04030105)+, Brule (04030106)+, Menominee (04030108)+, Cedar-Ford (04030109)+*, Escanaba (04030110)+*, Tacoosh-Whitefish (04030111)+, Fishdam-Sturgeon (04030112)+, Wolf (04030202)+, Muskegon (04060102)+*, Betsie-Platte (04060104)+*, Boardman-Charlevoix (04060105)+*, Manistique (04060106)+*, Brevoort-Millecoquins (04060107)+, St. Marys (04070001)+, Carp-Pine (04070002)+, Lone Lake-Ocqueoc (04070003)+*, Cheboygan (04070004)+*, Black (04070005)+, Au Sable (04070007)+*, Pine (04080202)+*, Lower Genesee (04130003)+*, Seneca (04140201)+*, Black (04150101)+*, Oswegatchie (04150302)+*, Grass (04150304)+*, Otter Creek (04150402)+*, Lamoille River (04150405)+, Lake Champlain (04150408)+*, St. Francois River (04150500)+
07 Upper St. Croix (07030001)+*, Upper Chippewa (07050001)+, Flambeau (07050002)+*, South Fork Flambeau (07050003)+, Upper Wisconsin (07070001)+
10 Middle Cheyenne-Spring (10120109)+, Rapid (10120110)+, Lower Belle Fourche (10120202)+, Redwater (10120203)+
14 Chinle (14080204)+*
15 Lower Colorado-Marble Canyon (15010001)+*, Havasu Canyon (15010004)+, Little Colorado headwaters (15020001)+, Lower Little Colorado (15020016)+, San Francisco (15040004)+, Black (15060101)+
19 Prince of Wales (19010103)+*, Kuiu-Kupreanof-Mitkof-Etolin-Zarembo-Wrangell Isla (19010202)+*, Baranof-Chichagof Islands (19010203)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
Technical Description:

A delicate, miniature, solitary (occasionally two) "ladys slipper" (7-16 cm), arising from a scape with a single, basal blue-green plantain-like leaf which withers soon after flowering. The lavender sepals look like a miniature hand drooping slightly towards the forest floor. The "slipper" is streaked, crimson-magenta with yellow "hairs" frontally. The capsule is ellipsoid, erect, 2.5 x 1.5 cm.

Ecology Comments:

CALYPSO grows primarily in the fall and early spring, blooming from late May to late June (Mousely 1924). The evergreen, solitary leaf, emerges in late August, overwinters, and shrivels soon after blooming. Capsules are set in June and July, and soon after there may be no visible signs of of this species. The new overwintering leaves usually begin to emerge in September (Caljouw 1981), but Vickery and Rooney (pers. observation) noted emerging leaves in mid August in Lee, Maine. Very few plants set fruit (Mosquin 1970). However, fairy slipper orchids produce thousands of seeds per capsule, which gives them the potential of good spread by seed.

Mousely (1924) reports that principal reproduction is by rhizomatous roots at the base of the tubers. Another factor contributing to the elusive qualities of this species is dormancy, one to several year periods being common (pers. obs.). Densities of this species vary from the usual one or two to the up to fifty plants per square foot reported by some references (Rooney, Gawler, Merry, Vickery pers. comm., Mosquin 1970). In Crystal Bog Preserve the population has fluctuated from one flowering plant in 1979 upwards to 12 blooming in spring of 1981; down to five flowers in spring of 1982. In fall of 1983 Mckellar & Rooney counted 40 sterile leaves and five plants with flower buds.

CALYPSO apparently is intolerant of soil temperatures in excess of 15 degrees C and of canopy cover less than 60% (Caljouw 1981). It is principally associated with THUJA OCCIDENTALIS - growing in the shaded duff with little or no herbaceous competition.

In several sites in Maine, the cover has been extensively damaged by spruce budworm recently, allowing light to penetrate to the forest floor. The spring of 1983 marked the lowest population of CALYPSO at these sites since its discovery in 1979 (Rooney). The decline of flowering plants probably reflects the damage done to the cover by the budworm and perhaps frost damage to the tubers. The winter of '82/'83 was distinguished by the absence of the usual protective blanket of snow.

Habitat Comments:

Most often found in cool, mature cedar swamps or on slopes of mixed coniferous growth underlain by some type of calcareous bedrock. At all known Maine stations but one, CALYPSO is associated with northern white cedar (THUJA OCCIDENTALIS). In the Rockies, CALYPSO prefers dry coniferous slopes. This element prefers moderate to well-drained sites with little herbaceous competition, wherever it grows - even in THUJA swamps it is usually found growing up on ridges, cedar butts, upon decaying logs or on gentle slopes.

Economic Attributes Not yet assessed
Management Summary
Stewardship Overview:

CALYPSO BULBOSA lives in vegetationally mature THUJA swamps in the East and in mountainous regions in the West. Most disturbances would be man-caused (trampling, logging). Population fluctuations in the absence of human activities are probably caused by periodic openings in the canopy allowing light to penetrate to the forest floor and thus increasing competition and substrate temperature.

Restoration Potential:

Vickery and Rooney feel that we do not have sufficient information about the sites in Maine to answer this question.

Preserve Selection & Design Considerations:

Enough buffer zone to ensure the protecton of the canopy must be provided.

Monitoring Requirements:

Since this element is everywhere rare and local in the northeast, large populations should be monitored. This probably is not necessary in the Rockies and further west, as CALYPSO is more plentiful in these regions.

Long term demographic studies would provide information regarding the longevity of this species, as well as providing information on CALYPSO's specific adaptions to competition and habitat changes.

At CALYPSO sites in Maine each sterile leaf or individual with a flower bud has been staked and labeled with a year and size/reproductive class code.

Monitoring Programs:

Vickery and Rooney (August, 1983) initiated demographic studies on all the large and reasonably stable CALYPSO sites in Maine (Lee, Scraggly and Webster Lakes and Crystal Bog Preserve).

Rooney and McKellar have monitored the population at Crystal Preserve since 1979.

Population/Occurrence Delineation Not yet assessed
Population/Occurrence Viability
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
NatureServe Conservation Status Factors Edition Date: 15Jun1987
NatureServe Conservation Status Factors Author: Ogle, Y. (1987), rev. D. Atwood; S. Rooney (1984); rev. L. Morse (2003)
Management Information Edition Date: 29Aug1984
Management Information Edition Author: SALLY ROONEY
Element Ecology & Life History Edition Date: 29Aug1984
Element Ecology & Life History Author(s): ROONEY, S.

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

  • Caljouw, C. 1981. Life history and management recommendations for Calypso, CALYPSO BULBOSA, in Scraggly Lake Public Lot, T7R8 WELS A report prepared for Bureau of Public Lands.

  • Flora of North America Editorial Committee. 2002a. Flora of North America North of Mexico. Vol. 26. Magnoliophyta: Liliidae: Liliales and Orchidales. Oxford Univ. Press, New York. xxvi + 723 pp.

  • Judziewicz, E. J. 2001. Flora and vegetation of the Grand Traverse Islands (Lake Michigan), Wisconsin and Michigan. Michigan Botanist 40: 81-208.

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Luer, C.A. 1975. The native orchids of the United States and Canada excluding Florida. New York Botanical Garden. 361 pp.

  • Mosquin, T. 1970. The reproductive biology of CALYPSO BULBOSA (Orchidaceae). Canadian Field-Naturalist 84:291-296.

  • Mousely, H. 1924. CALYPSO. Jour. of N.Y. Bot. Garden. vol. 25 290: 25-30.

  • Stoutamire, W.P. 1971. Pollination in temperate American orchids. Proc. 6th, World Orchid Conference 223-243.

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