1. Family: Orchidaceae Juss.
    1. Genus: Cypripedium L.
      1. Cypripedium calceolus L.

        The lady's slipper orchid is one of the best known and most widely illustrated of all flowering plants. The earliest record of this fine orchid is Conrad Gessner’s fine watercolour illustration of 1541, which was sadly not published until the 18th Century by Camerarius.

    [KSP]

    Kew Species Profiles

    General Description
    The lady's slipper orchid is one of the best known and most widely illustrated of all flowering plants.

    The lady's slipper orchid is one of the best known and most widely illustrated of all flowering plants. The earliest record of this fine orchid is Conrad Gessner’s fine watercolour illustration of 1541, which was sadly not published until the 18th Century by Camerarius.

    The species was first reported as a native European plant by the herbalists Dodoens, L'Obel and Clusius. The fine woodcuts in their works show an immediately recognisable likeness, so much so that they have since been reproduced many times. Carl Linnaeus, the famous Swedish botanist, named it as Cypripedium calceolus in his Species Plantarum in 1753.

    Species Profile
    Geography and distribution

    Cypripedium calceolus is widely distributed, ranging from Spain, the British Isles and Scandinavia in western Europe across to north-eastern China, eastern Siberia and Sakhalin Island. It may also occur on Honshu in Japan.

    In Europe it is found from sea level in the north up to over 2000 m above sea level in the Alps. It favours limestone and is found in deciduous, mixed deciduous and coniferous woods, growing in light to deep shade. In eastern Siberia it is found growing in neutral or slightly acidic (pH 6) conditions.

    Description

    The lady's slipper orchid is a long-lived herbaceous perennial which produces new growths from a rhizome (swollen underground stem) each season. It grows up to 60 cm tall, and the stems have a covering of glandular hairs. Each stem has three to four leaves, which are strongly pleated and often have upcurved sides. The leaves can reach 18 cm in length and 9 cm in breadth. The inflorescence (flower stalk) is one- to two-flowered with leaf-like bracts. The flowers are showy. The sepals and petals are maroon (rarely green) and often spirally twisted. The sac of the slipper-like lip is yellow, and spotted inside with red. It is related to C. macranthos and can form hybrids where the species occur together in the eastern part of the range of C. calceolus . Cypripedium calceolus is quite variable in the wild. Plants may bear up to three flowers on a spike. Flowers can have green or yellow, rather than maroon, sepals and petals and a white, rather than a yellow, lip.

    Threats and conservation

    In England, Cypripedium calceolus was never common and was over-collected to the point of almost being extinct by the first half of the twentieth century. It clung on at one site, and has since been successfully propagated and reintroduced. Elsewhere, it ranges from being extremely rare (for example in Denmark) or extinct (for example in Greece) to occurring in relatively large populations (for example in Poland and Austria). It serves as a flagship species for plant conservation in many of the countries in which it occurs.

    Cultivation of lady's slipper orchid at Kew

    This species was collected to the brink of extinction in Britain. When a single plant was rediscovered, a group of interested individuals and organisations formed the Cypripedium Committee, to guard the remaining plant and develop a conservation strategy.

    After several years of protection from further damage, the wild plant recovered some of its vigour and started to flower again. The flowers were hand pollinated, and the resulting seeds were then sent to Kew.

    Orchid seeds are tiny and dust-like, and have stringent requirements for germination, and Cypripedium calceolus is no exception. In the Micropropagation Laboratory at Kew, the seeds were sterilised in a weak bleach solution and sown onto sterile agar jelly in Petri dishes, with nutrients added. These initial attempts at propagation were unsuccessful.

    Finally, success was achieved when seeds were collected before they were fully developed. The seeds were collected between 40 and 50 days after pollination, and sown onto an agar medium developed by Svante Malmgren, containing amino acids, vitamins and pineapple juice. The seeds were then placed in the dark. Almost all the seeds germinated within two months of sowing. This method is now used routinely for the germination of Cypripedium seeds.

    When the seedlings have a shoot and two roots, they are moved into honey jars containing the same agar medium. Then, after one or two years in the laboratory, the plantlets can be grown on in pots. Various types of pot have been tried at Kew, and plastic, five-inch, 1/2 pots are currently used.

    A variety of compost mixes have been tested. Compost containing loam helps retain water and organic components may support fungi, which are thought to provide nutrients for the plants. The pots are usually checked twice a week to see if they need watering. Rainwater is best, and less water is needed in winter. Plants thrive best when planted out in a suitable compost under light shade in a woodland garden.

    Kew and Natural England are working together to reintroduce seedlings into locations where the species has died out. Some reintroduced plants have flowered and in 2009, seed pods formed after natural pollination by insects.

    Cultivation

    The lady’s slipper orchid has been in cultivation since at least 1731, when there is a record of Philip Miller growing it at the Chelsea Physic Garden. It has a reputation of being difficult to grow for any length of time. At Kew, following experimentation in our micropropagation laboratory, we have managed to successfully propagate the plant and have developed a method of germination which is now routinely in use.

    The plants can be grown outside in cold frames, and benefit from a cold winter. Cypripedium calceolus is a woodland species, and does not demand strong light, and so it can be grown on the north side of a building. If grown in a cold frame it should be covered by shade cloth in the summer. The plants are dormant over winter and in leaf over summer, and flowering begins in May.

    This species is susceptible to aphids, which can transmit viruses to the plant. Other pests include slugs and snails, which particularly enjoy orchids, and small rodents and birds that sometimes disturb pots.

    Orchids in the lab

    Lady’s slipper orchids are common across the Americas, and also in Europe and temperate and eastern Asia, south to the Himalayas. However, by the early 1980s, the British lady’s slipper, Cypripedium calceolus , was down to a single flowering individual in the wild. Over-collecting by orchid enthusiasts and the disappearance of suitable habitats had seen numbers dwindle to the edge of extinction, so in 1983 Sir Robert and Lady Sainsbury funded a project at Kew’s micropropagation unit to try to improve techniques for growing wild orchids in artificial conditions.

    Orchids often grow in cooperation with fungi called ‘mycorrhizal fungi’, which produce the nutrients the plant needs. In return, the orchid will later share food it has made by photosynthesis – something the fungi cannot do. The problem with growing orchids in the lab is identifying the right fungi for any particular orchid, which can be difficult. In many cases, the fungi are actually essential for germinating the seed of the orchid.

    The most usual technique is to take some cells from the roots of actively growing orchid plants, as the fungi actually grow inside the roots. However in some cases, no appropriate fungus could be found. This was true for the British lady’s slipper. But luckily, trial and error revealed that sowing immature seed from green capsules produced good results without the right fungi, especially if the seed trays were chilled after seeding.

    The tiny seeds were sown into a layer filled with amino acids and mineral salts that the plants would need to grow, and then were kept in huge fridges to maintain the cool temperature, which seems to be necessary. Thousands of seedlings have now been raised so that the little plants can be planted out in the wild. The locations of these plantings remain secret in the hope of protecting the young seedlings from collectors. They are guarded by volunteers who are also trained in techniques of pollination, to ensure as much seed as possible is produced from the mature plant for the future.

    Orchid scene investigation

    There are fifty species of wild orchid growing in Britain, about a third of which are listed as threatened. Nature conservation organisations are keen to preserve orchids, which are some of our most spectacular wild flowers. So Mike Fay of Kew’s Jodrell Laboratory and his team have been using DNA fingerprinting to look at the question of which orchids exactly are growing wild in the UK, and which should be top priority.

    But their DNA analysis has revealed some interesting problems for orchid conservationists. Mike Fay and his team looked at the early purple orchid, Orchis mascula , and DNA evidence from the plants’ chloroplasts suggests that there are two distinct groups of early purple orchids in the UK. The main UK population is closely related to plants in Brittany and Normandy, just across the channel. But the populations that grow in the south-west of England are more closely related to early purple orchids in Portugal and Spain than they are to French plants. So, the UK populations would seem to have come to these islands in two separate migrations. Conservation organisations can now set their targets to reflect the fact that there are two gene pools which need conserving, not just one.

    O. militaris , the military orchid, revealed another dilemma. Two populations of this rare orchid are currently known in the Chilterns, one large (about 200 plants) and one small (fewer than ten individuals). However DNA analysis by Fay’s team revealed that every plant in the large population is related back to a single ancestor, whereas in the smaller population each plant is very genetically distinct. This means that there is far more biodiversity worth preserving in the much smaller population.

    Research like this can help conservation organisations concerned with wild orchids set much more useful targets for their work and can aid them to think about how to set their priorities for the future.

    Phil Cribb on Kew's orchid work

    Lady's slippers or slipper orchids comprise only a small fraction of the world's orchid flora: some 180 species out of a total of 25,000 species. However, this charismatic group has attracted the interest and passion of many of the leading orchid growers and scientists for the past 150 years or more.

    I was first attracted to lady's slipper orchids when I was appointed as Kew's representative on the Nature Conservancy’s (now English Nature) Cypripedium Committee, a group of ten people who looked after the sole remaining native plant of Cypripedium calceolus ‘somewhere in the North of England’. From that point on, now over 35 years ago, I was hooked and have studied and searched for these elusive orchids all over the world, from the south-west Pacific islands of New Guinea and the Solomon Islands, throughout south and south-east Asia across to the tropical Americas, Mexico and North America.

    Despite their popularity, the discovery of new species of orchid continues at a steady rate of about two per year, especially in the Far East and in the tropical Americas. Some have proved to be sensational plants, amongst the most spectacular of all orchid species.

    This has kept the profile of slipper orchids high in the horticultural world. Since slipper orchids tend to grow in very specific habitats and in small colonies, rarely exceeding a thousand plants, their horticultural popularity has made them amongst the world's most threatened plants. Even today new species are almost exterminated as soon as they are discovered.

    Scientific knowledge of slipper orchids has also grown dramatically in recent years since the advent of DNA analysis. We now understand the evolutionary relationship of the slipper orchids themselves, their relationship to other orchids (indeed, some doubted if they were orchids), and their antiquity. Field work has elucidated their life cycle, pollination biology and population biology.

    The regenerative power of some over-collected species in the wild, together with recent advances in the propagation of slipper orchids from seed and the ease with which many can be cultivated, suggests that the future of some of the rarer species is not as bleak as was once thought.

    Millennium Seed Bank: Seed storage

    Kew's Millennium Seed Bank Partnership aims to save plant life worldwide, focusing on plants under threat and those of most use in the future. Seeds are dried, packaged and stored at a sub-zero temperature in our seed bank vault.

    Number of seed collections stored in the Millennium Seed Bank:  One

    Distribution
    China, Denmark, Japan, Norway, Spain, Sweden, United Kingdom
    Ecology
    Various calcareous environments, often in open woodland.
    Conservation
    Classified as Least Cornern according to IUCN Red List criteria on a global scale, although the species is rare and declining in some areas such as Bulgaria and the UK. Cypripedium calceolus is generally widely distributed in Europe and temperate Asia.
    Hazards

    Some people have reported an allergic reaction to the glandular hairs on the stems.

    [C-EM]
    Ecology

    In partial shade in open woodland and scrub under conifers, species of Quercus (oak), Fraxinus (ash), and Corylus (hazel), in lime-rich soils over limestone, rarely in full sunlight at higher elevations; sea level to 2500 m. Perner (pers. comm.) reports that in eastern Siberia it is found growing in neutral or slightly acidic (pH 6) conditions.

    General Description

    A terrestrial herb 15-60 cm tall, with a short stout creeping rhizome and fibrous roots, often forming clumps. Erect stems glandular-pubescent, terete, leafy above. Leaves three to four, suberect-spreading, strongly pleated, often with upcurved sides, elliptic to ovate, rarely lanceolate, acute to acuminate, 6-18 cm long, 3-9 cm wide, green. Inflorescence one- or less commonly two-flowered; bracts leaf-like, lanceolate to ovate or elliptic-ovate, acuminate, 1-6 cm long. Flowers showy, the sepals and petals maroon or rarely green, the lip yellow spotted within with red, the staminode yellow spotted with red; pedicel and ovary c. 3 cm long, shortly glandular- pubescent. Dorsal sepal suberect, elliptic-lanceolate or ovate, acuminate, 3.5-5 cm long, 1.5-2 cm wide, rarely slightly twisted towards apex, ciliate. Synsepal elliptic-lanceolate or lanceolate, acuminate and bidenticulate at apex, 3.5-5 cm long, 1.5-1.8 cm wide, the sides recurved somewhat, ciliate. Petals deflexed at c. 45° to horizontal, spirally twisted one to three times, linear-tapering, acute or acuminate, 3.5-6~5cm long, 0.5-0.7 cm wide, pubescent at base within. Lip glossy, ellipsoidal to obovoid, 3-5.3 cm long, 2.5-3 cm wide, the margins smoothly incurved with a fold at the base on each side. Column c. 1 cm long; staminode shortly stalked, longitudinally channelled, slightly concave at apex, obovate with a cordate base, blunt, 1-1.2cm long, 0.7-0.9 cm wide; filament extending beyond anthers, acute.

    DISTRlBUTION. Europe (from northern England and Scandinavia, eastern France, NE. Spain, Germany, N. Italy and N. Greece (now extinct) and eastern Europe eastward to European Russia, Siberia, N. Sakhalin, Korea, NE. China (Heilongjiang, Jilin, Nei MonggoI), andJapan (Rebun Isl., fide S. Kawahara pers. comun.).

    Images

    Distribution

    Found In:

    Altay, Amur, Austria, Baltic States, Belarus, Belgium, Bulgaria, Buryatiya, Central European Rus, Chita, Czechoslovakia, Denmark, East European Russia, Finland, France, Germany, Great Britain, Greece, Hungary, Inner Mongolia, Irkutsk, Italy, Japan, Khabarovsk, Korea, Krasnoyarsk, Krym, Manchuria, Mongolia, North European Russi, Northwest European R, Norway, Poland, Primorye, Romania, Sakhalin, South European Russi, Spain, Sweden, Switzerland, Tuva, Ukraine, West Siberia, Yakutskiya, Yugoslavia

    Common Names

    English
    Lady's slipper orchid

    Cypripedium calceolus L. appears in other Kew resources:

    Date Identified Reference Herbarium Specimen Type Status
    Corkhill, P., United Kingdom 64477.000
    Mitchell [104] 71424.000
    Fay [19106] 73621.000
    Hooker, W.J. [s.n.] K000363718
    Lang, A.F. [s.n.] K000363719
    s.coll. [s.n.], Austria K000363720
    Jacquin, N.N.J.von [s.n.], Germany K000363721
    59701.000
    K000363741
    Barneby, T.P. [3], Italy 31612.000
    72071.000
    Sprunger, S. [s.n.], Germany 57257.000
    19472.000

    First published in Sp. Pl.: 951 (1753)

    Accepted in:

    • [1] (2016) Flora of Japan IVb: 1-335. Kodansha Ltd., Tokyo
    • [3] Chang, C.S., Kim, H. & Chang, K.S. (2014) Provisional checklist of vascular plants for the Korea peninsula flora (KPF) . DESIGNPOST
    • [5] Dimpoulos, P., Raus, T., Bergmeier, E., Constantinidis, T., Iatrou, G., Kokkini, S., Strid, A., & Tzanoudakis, D. (2013) Vascular plants of Greece. An annotated checklist . Botanic gardens and botanical museum Berlin-Dahlem, Berlin and Hellenic botanical society, Athens
    • [9] (2009) Flora of China 25: 1-570. Missouri Botanical Garden Press, St. Louis
    • [10] G.I.R.O.S. (2009) Orchidee d'Italia . Il Castello srl, Italy
    • [11] Castroviejo, S. & al. (eds.) (2005) Flora Iberica 21: 1-366. Real Jardín Botánico, CSIC, Madrid
    • [12] Govaerts, R. (2003) World Checklist of Monocotyledons Database in ACCESS . The Board of Trustees of the Royal Botanic Gardens, Kew
    • [13] Govaerts, R. (1999) World Checklist of Seed Plants 3(1, 2a & 2b): 1-1532. MIM, Deurne

    Literature

    • [2] Popova, E., Kim, H.H., Saxena, P.K., Engelmann, F. & Pritchard, H.W. (2016). Frozen beauty: the cryobiotechnology of orchid diversity. Biotechnology Advances 34: 380-403.
    • [4] Marks, T.R., Seaton, P.T. & Pritchard, H.W. (2014). Desiccation tolerance, longevity and seed-siring ability of entomophilous pollen from UK native orchid species. Annals of Botany 114: 561-569.
    • [6] Nadarajan, J., Wood, S., Marks, T.R., Seaton, P.T. & Pritchard, H.W. (2011). Nutritional requirements for in vitro seed germination of 12 terrestrial, lithophytic and epiphytic orchids. Journal of Tropical Forest Science 23: 204-212.
    • [7] Seaton, P.T., Hu, H., Perner, H. & Pritchard, H.W. (2010). Ex Situ conservation of orchids in a warming world. The Botanical Review 76: 193-203.
    • [8] Fay, M.F. et al. Genetic diversity in Cypripedium calceolus (Orchidaceae) with a focus on north-western Europe, as revealed by plastid DNA length polymorphisms. Annals of Botany 104, 517-25 (2009).
    • [14] Linnaeus, C. Original description of Cypripedium calceolus. (1753).at

    Sources

    Kew Names and Taxonomic Backbone
    The International Plant Names Index and World Checklist of Selected Plant Families (2017). Published on the internet at http://www.ipni.org and http://apps.kew.org/wcsp
    [A] See http://kew.org/about-kew/website-information/legal-notices/index.htm You may use data on these Terms and Conditions and on further condition that: The data is not used for commercial purposes; You may copy and retain data solely for scholarly, educational or research purposes; You may not publish our data, except for small extracts provided for illustrative purposes and duly acknowledged; You acknowledge the source of the data by the words "With the permission of the Trustees of the Royal Botanic Gardens, Kew" in a position which is reasonably prominent in view of your use of the data; Any other use of data or any other content from this website may only be made with our prior written agreement. http://creativecommons.org/licenses/by-nc-sa/3.0
    [B] © Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

    Kew Species Profiles
    Kew Species Profiles
    [C]
    [D] http://creativecommons.org/licenses/by-nc-sa/3.0

    Kew Library Art and Archives
    [E] Digital Image © Board of Trustees, RBG Kew http://creativecommons.org/licenses/by/3.0/

    Cypripedioideae: e-monocot.org
    [F] All Rights Reserved