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Calypso Orchid (Calypso bulbosa)

Life history

Species overview

Calypso Orchid (Calypso bulbosa), a Wisconsin Threatened plant, is found only in old growth white cedar swamps. Blooming occurs early May through July; fruiting occurs late June through late July. The optimal identification period for this species is late May through early June.

Synonyms: Cytherea bulbosa, Calypso bulbosa var. americana


  • Distinguishing characteristics: Very small orchid bearing a solitary flower with pale purple, lance-shaped petals above, a pinkish pouch-shaped petal below and a white lip with a clump of yellow hairs; single basal leaf 3 to 5 cm long and round to egg-shaped, often notched at the base.
  • Flower characteristics: Flower solitary; petals pale purple to white, lance-shaped above and with a pinkish-white pouch-shaped petal below that is covered in dark red stripes; a white lip extends from the front of the pouch and a clump of yellow hairs protrude from the lip.
  • Fruit characteristics: Capsule erect, cylindrical to lanceoloid, ribbed, 2 to 3 cm long.
  • Leaf characteristics: Single, 3 to 5 cm long, round to egg-shaped, often notched at the base; petiole usually about 3 to 5 cm long.


  • Blooming phenology: early May through July
  • Fruiting phenology: late June through late July
  • Optimum time to identify: The optimal identification period for this species is late May through early June


  • Growth form: Forb-erect
  • Vegetative reproduction:
  • Life cycle: Perennial
  • Comments: Associated Species: Thuja occidentalis, Coptis trifolia, Polygala pauciflora, Linnaea borealis, Cornus canadensis, Mitella nuda, Gaultheria hispidula, Platanthera obtusata, Carex disperma, C. trisperma.

State status

Status and Natural Heritage Inventory documented occurrences in Wisconsin

The table below provides information about the protected status - state and federal - and the rank (S and G Ranks) for Calypso Orchid (Calypso bulbosa). See the Working List Key for more information about abbreviations. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. The map is provided as a general reference of where this species has been found to date and is not meant as a range map.

Documented locations of Calypso bulbosa in the Natural Heritage Inventory Database as of July 2015.

Summary Information
State StatusTHR
Federal Status in Wisconsinnone
State RankS2
Global RankG5
Tracked by NHIY

Habitats and landscapes

The Natural Heritage Inventory has developed scores indicating the degree to which each of Wisconsin's rare plant species is associated with a particular natural community or ecological landscape. This information is similar to that found in the Wildlife Action Plan for animals. As this is a work in progress, we welcome your suggestions and feedback.

General habitat information

  • Habitat description: Found only in old growth white cedar swamps.
  • Soils: Moist soils.

Natural communities

This table lists the natural communities that are associated with Calypso Orchid. Scores for natural community associations are: "significant" association (score=3), "moderate association" (score=2) or the species can be present but is only weakly associated with the community (score=1).

Natural communities score
Northern Wet-mesic Forest 3

Ecological landscapes

This table lists the ecological landscape association scores for Calypso Orchid. The scores (3=High, 2=Moderate, 1=Low, 0=None) also correspond to the map.

Map of the Ecological Landscapes of Wisconsin.

Species guidance

The Endangered Resources Program has developed avoidance measures and management guidelines for plants on the Natural Heritage Working List. These are a work in progress, and we welcome your suggestions and feedback. Sources used in developing this information can be found here.

Avoidance measures

These are specific actions designed to avoid "take" (mortality) of this species.

  • Avoid broadcast spraying of herbicides; use care with spot spraying.
  • Avoid known individual plant locations and conduct operations elsewhere when they are least likely to cause damage. Ideally, this would involve frozen, snow-covered ground. However, in areas of the state where frozen conditions are unreliable, very dry soils late in the growing season might be the best available alternative. Consult with a biologist, if needed.

Management guidance

Management guidelines are additional considerations that may help maintain or enhance habitat for this species

  • This species is intolerant of canopy removal. Therefore, single-tree selection is recommended as long as the microclimate is not impacted significantly.
  • Avoid rapid and dramatic reductions in canopy cover or basal area in wet areas to reduce risk of swamping.
  • Follow BMPs, especially around streams and use care near ravines, steep slopes, cliffs, rock outcrops, etc.
  • Minimize disturbance to hydrology, including soil disturbance from rutting.
  • Maintain high forest canopy cover; this species requires shaded habitat conditions.


Calypso Orchid Photo.

The fairy slipper is a rare orchid that grows in rich conifer swamps.

Photo by Thomas Meyer, Wisconsin DNR.

Calypso Orchid Photo.

Fairy slipper is a rare orchid that is most often associated with older boreal forest, white-cedar swamps or stands of hemlock-hardwoods.

Photo by Thomas Meyer, Wisconsin DNR.

Calypso Orchid Photo.

Photo by Thomas Meyer, Wisconsin DNR.

Calypso Orchid Photo.

Photo © Tom Gibson.

Calypso Orchid Photo.

Photo © Robert H. Read.

Support for Wisconsin's rare plant information has been provided by the Division of Forestry, the Endangered Resources Fund and the Wisconsin Rare Plant Preservation Fund. To donate, visit the Natural Resources Foundation of Wisconsin [exit DNR].

Last revised: Wednesday, May 05, 2021
Southwest Savanna Southern Lake Michigan Coastal Western Coulees and Ridges Southeast Glacial Plains Central Sand Hills Central Lake Michigan Coastal Central Sand Plains Northern Lake Michigan Coastal Northern Lake Michigan Coastal Northeast Sands Western Prairie North Central Forest Northern Highlands Northwest Lowlands Northwest Sands Northwest Lowlands Superior Coastal Plains Forest Transition