Cypripedium

The Cypripedium are terrestrial and, as with most terrestrial orchids, the rhizome is short and robust, growing in the uppermost soil layer. The rhizome grows annually with a growth bud at one end and dies off at the other end. The stem grows from the bud at the tip of the rhizome. Most slipper orchids have an elongate erect stem, with leaves growing along its length. But the mocassin flower or pink lady's slipper (Cypripedium acaule) has a short underground stem with leaves springing from the soil. The often hairy leaves can vary from ovate to elliptic or lanceolate, folded (plicate) along their length. The stems lack pseudobulbs.

The inflorescence is racemose. It can carry one to twelve flowers, as in Cypripedium californicum. But most species have one to three flowers. There are three sepals, with, in most species, the two lateral ones more or less fused. The flower has three acute petals with the third a striking slipper-shaped lip, which is lowermost. The sepals and the petals are usually similarly colored, with the lip in a different color. But variations on this theme occur. The aspect of the lip of different species can vary a great deal. As with all orchids, it is specially constructed to attract pollinators, which it traps temporarily. The flowers show a column with a unique shield-like staminode. The ovary is 3-locular (with three chambers).

Comparison between a DNA-analysis and the morphological characteristics in this genus has shown that there is a high degree of divergence between the two, probably due to long periods of isolation or extinction of intermediate forms. The Eurasian species with yellow or red flowers form a distinct group from the North American species with yellow flowers. The Mexican Pelican Orchid (Cypripedium irapeanum) and the California lady's slipper (Cypripedium californicum) are probably the first diverging line. They share several similarities with their sister group Selenipedium.

There are 58 currently recognized species and nothospecies (naturally occurring hybrids) recognized in this genus, as of May 2014:

The genus has a long history of use, dating back 2,500 years to the Far East, where they were used medicinally.

Several orchid species thought to be extinct in the United Kingdom including one native species in this genus have been found in habitat and are currently the subject of aggressive conservation efforts to protect and restore these showy plants to their native ranges.{{Cite web|first=Juliette |last=Jowit |url=https://www.theguardian.com/environment/2010/mar/08/ghost-orchid-extinction |title=Ghost orchid comes back from extinction. |work=The Guardian |date=3 August 2010|access-date=1 June 2015}}

The following have received the Royal Horticultural Society's Award of Garden Merit:-

• Cypripedium formosanum{{cite web | url = https://www.rhs.org.uk/Plants/84011/Cypripedium-formosanum/Details | title = Cypripedium formosanum | publisher = RHS | access-date = 5 May 2020}}
• Cypripedium Hank Small gx{{cite web | url = https://www.rhs.org.uk/Plants/117068/Cypripedium-Hank-Small-gx/Details | title = Cypripedium Hank Small gx | publisher = RHS | access-date = 5 May 2020}}
• Cypripedium Michael gx{{cite web | url = https://www.rhs.org.uk/Plants/203275/Cypripedium-Michael-gx/Details | title = Cypripedium Michael gx | publisher = RHS | access-date = 5 May 2020}}
• Cypripedium reginae{{cite web | url = https://www.rhs.org.uk/Plants/5225/Cypripedium-reginae/Details | title = Cypripedium reginae | publisher = RHS | access-date = 5 May 2020}}
• Cypripedium Sabine gx{{cite web | url = https://www.rhs.org.uk/Plants/203276/Cypripedium-Sabine-gx/Details | title = Cypripedium Sabine gx | publisher = RHS | access-date = 5 May 2020}}

• Phillip Cribb & Peter Green (1997). The Genus Cypripedium (a botanical monograph). Kew Royal Botanic Gardens, Timber Press {{ISBN|0-88192-403-2}}
• Pridgeon, A.M.; Cribb, P.J.; Chase, M.W. & F. N. Rasmussen (1999): Genera Orchidacearum Vol.1, page: 114 ff., Oxford U. Press. {{ISBN|0-19-850513-2}}

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• {{Wikispecies-inline|Cypripedium|Cypripedium}}
• [http://www.w-frosch.de Cypripedium - Infos by Mr. Frosch]
• [http://www.guegel.com/ernst/orchideen/china/index.htm Photos of Chinese Slipper Orchids]
• [http://www.alpine-plants-jp.com/art/kumaga1.htm Cypripedium japonicum] [http://www.alpine-plants-jp.com/art/hoteiat1.htm Cypripedium macranthum var. hotei-atsumorianum] Images of Japanese Cypripedium
• [https://web.archive.org/web/20120212120131/http://www.orchidsrepbiol.de/cgi-bin/img_db/img_displayTaxon.pl?db=Cypripedium Cypripedium picture database]

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Category:Orchid genera

Category:Taxa named by Carl Linnaeus