Calypso is a genus of orchids containing one species, Calypso bulbosa, known as the calypso orchid, fairy slipper or Venus's slipper. It is a perennial member of the orchid family found in undisturbed northern and montane forests. It has a small pink, purple, pinkish-purple, or red flower accented with a white lip, darker purple spottings, and yellow beard. The genus Calypso takes its name from the Greek signifying concealment, as they tend to favor sheltered areas on conifer forest floors. The specific epithet, bulbosa, refers to the bulb-like corms.
Description
Calypso bulbosa is a low growing herbaceous plant with a nearly egg-shaped underground storage organ called a corm. It is encased in dead leaf sheaths and has elongated roots. Calypso orchids are typically 8 to 20 cm in height. Plants have a single leaf that measures 1 to 6.5 centimeters long with a width of 1.2 to 5.2 cm. The leaf is suborbiculate, nearly circular, or ovate, egg shaped in outline. The base of the leaf is often cordate, having an indentation like the top of a heart. The leaf often has a very long petiole, a leaf stalk attaching it to the plant. The leaf sprouts in the autumn and remains green over the winter. It withers a short time after flowering.
Plant blooms with a purple-pink hermaphroditic, zygomorphic and threefold flower. The protruding petals and sepals are pink to purple in color, about 10 to 12 millimeters long and about 2 to 4 millimeters wide. The lip (labellum) is white to pink with pink or yellow spots. It has a wide, shoe-shaped cavity in the back and is about 15 to 25 millimeters long. They do not bloom until May and June usually after snow melt. A new bulb is formed by the plant each year, but bulbs from one or two years prior can remain attached and firm. Plants seldom live for longer than five years.
Taxonomy and systematics The chromosome count is 2n = 28. Since the orchid seed does not provide any nutrient tissue, germination only takes place when infected by a mycorrhizal root fungus.
Taxonomy The accepted generic name Calypso was described in 1808 by the English gardener Richard Anthony Salisbury in the work Paradisus Londinensis. It was published with the then-director of the Royal Botanic Gardens in London, William Jackson Hooker (1785–1865). In 1905, Homer Doliver House proposed that the genus be renamed as Cytherea because of the earlier publication of Calypso by Louis-Marie Aubert du Petit-Thouars 1804, regarded as a synonym of Salacia. In 1930 it was made a conserved name by the International Botanical Congress.
The following generic names have been published as synonyms: Cytherea (1812) Orchidium (1814) Calypsodium (1829) Norna (1833)
Calypso bulbosa was assigned to the genus Cypripedium in 1753 by Carl von Linné in Species Plantarum. It was moved to the genus Calypso by the botanist William Oakes 1842.
Varieties Four varieties and one nothovariety, a variety of hybrid origin that is established in the wild, are recognized: Image Variety DistributionCalypso bulbosa var. americana (R.Br.) Luer most of Canada, western and northern United StatesCalypso bulbosa var. bulbosa Sweden, Finland, Baltic States, much of Russia, Mongolia, KoreaCalypso bulbosa nothovar. kostiukiae Catling Alberta (C. bulbosa var. americana × C. bulbosa var. occidentalis)Calypso bulbosa var. occidentalis (Holz.) Cockerell from Alaska and British Columbia south through the Cascades, Rockies, and Sierra Nevada to CaliforniaCalypso bulbosa var. speciosa (Schltr.) Makino Japan, China (Gansu, Jilin, Nei Mongol, Sichuan, Tibet, Yunnan)
Synonyms Calypso bulbosa has synonyms of the species or one of its four varieties, including 16 species.
Table of Synonyms Name Year Rank Synonym of: Notes Calypso americana 1813 species var. americana ≡ hom. Calypso borealis 1808 species C. bulbosa ≡ hom., nom. superfl. Calypso bulbosa f. albiflora 1995 form var. americana = het. Calypso bulbosa subsp. americana 2010 subspecies var. americana ≡ hom. Calypso bulbosa f. americana 1995 form var. americana ≡ hom. Calypso bulbosa f. biflora 2004 form var. americana = het. Calypso bulbosa f. candida 1945 form var. bulbosa = het. Calypso bulbosa f. nivea 1995 form var. occidentalis = het. Calypso bulbosa subsp. occidentalis 1963 subspecies var. occidentalis ≡ hom. Calypso bulbosa f. occidentalis 1895 form var. occidentalis ≡ hom. Calypso bulbosa f. rosea 1995 form var. americana = het. Calypso occidentalis 1898 species var. occidentalis ≡ hom. Calypso speciosa 1919 species var. speciosa ≡ hom. Calypsodium boreale 1829 species C. bulbosa ≡ hom., nom. superfl. Cymbidium boreale 1799 species C. bulbosa ≡ hom., nom. superfl. Cypripedium bulbosum 1753 species C. bulbosa ≡ hom. Cytherea borealis 1812 species C. bulbosa ≡ hom., nom. superfl. Cytherea bulbosa 1905 species C. bulbosa ≡ hom. Cytherea bulbosa var. occidentalis 1915 variety var. occidentalis ≡ hom. Cytherea occidentalis 1906 species var. occidentalis ≡ hom. Cytherea speciosa 1929 species var. speciosa ≡ hom. Limodorum boreale 1805 species C. bulbosa ≡ hom., nom. superfl. Norna borealis 1833 species C. bulbosa ≡ hom., nom. superfl. Norna borealis var. americana 1826 variety var. americana ≡ hom. Norna borealis var. asiatica 1826 variety var. bulbosa = het. Norna borealis var. europaea 1826 variety C. bulbosa ≡ hom., not validly publ. Orchidium americanum 1841 species var. americana ≡ hom. Orchidium arcticum 1814 species C. bulbosa ≡ hom., not validly publ. Orchidium boreale 1816 species C. bulbosa ≡ hom., nom. superfl. Notes: ≡ homotypic synonym; = heterotypic synonym
Names The genus Calypso is named in reference to the nymph Calypso, whose name means concealment. The habitat of these plants in the deep woods habitat metaphorically hides them from plant hunters. The species name, bulbosa, means possessing a bulb, referring to its growth habit. Calypso bulbosa is known by the common names fairy slipper, fairyslipper orchid, and fairy-slipper orchid, due to the prominent lower lip of the flower resembling a slipper. Similarly it is known as Venus slipper or Venus' slipper, but this name is also applied to orchids of the genus Cypripedium because of the mythological association with the goddess Venus. It is also known as angel slipper, slipper orchid, redwoods orchid, deer-head orchid, and calypso.
Range and habitat
This species' range is circumpolar, extending around the northern hemisphere. In Europe this includes just Sweden, Finland, the Baltic states, and the northern parts of European Russia. It includes California, the Rocky Mountain states and most of the most northerly states of the United States; most of Canada; China, Mongolia, Korea and Japan—see external links for map. It is found in subarctic swamps and marshes as well as shady places subarctic coniferous forests.
Conservation Although the calypso orchid's distribution is wide, it is very susceptible to disturbance. The conservation organization NatureServe evaluated the species in 2025 and found it to be secure at the global level (G5). However, in the United States they found it to be vulnerable (S3) in Arizona, Wyoming, South Dakota, Minnesota, and Maine. In two other states, Wisconsin and Michigan, they rated it as imperiled (S2). In Canada it also is rated as vulnerable in Saskatchewan and the Yukon Territory and imperiled in New Brunswick. More critically it is critically imperiled (S1) on the Island of Newfoundland and possibly locally extinct in Nunavut.
In Sweden it was listed as vulnerable in the 2020 Swedish Red List. Similarly, Finland evaluated it as vulnerable in the 2019 national Red Book.
Ecology At least near Banff, Alberta, the calypso orchid is pollinated by bumble bees (Bombus (Pyrobombus) and B. Psithyrus). It relies on "pollination by deception", as it attracts insects to anther-like yellow hairs at the entrance to the pouch and forked nectary-like structures at the end of the pouch but produces no nectar that would nourish them. Insects quickly learn not to revisit it. Avoiding such recognition may account for some of the small variation in the flower's appearance. Summarized by Coleman and by Boyden
Uses Attempts at garden cultivation are not successful and transplanting usually will kill plants. The structure of the corms suggest that the species is dependent on mycorrhizal relationships with soil funguses that are lost during transplantation. The corms have been used as a food source by North American native peoples. The Nlaka'pamux of British Columbia used it as a treatment for mild epilepsy.
References Citations
Sources Books
Journals
Web sources
External links
Map of distribution Jepson Manual treatment of the species Wild orchid of Japan