Orchids Wiki
Cypripedium arietinum

Cypripedium arietinum.jpg

Scientific Classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Liliopsida
Order: Asparagales
Subfamily: Cypripedioideae
Tribe: Cypripedioideae
SubTribe: Cypripediinae
Genus: Cypripedium
Species: Cyp. arietinum
Binomial name
Cypripedium arietinum
R. Br. 1813

Cypripedium arietinum, is an orchid that is native to the alvars around the Great Lakes in North America.


The plant grows to 10-40 cm, and the flowers may reach 1-2 cm (0.5-0.75 in). It flowers from May to June, producing brownish-green fragrant flowers with a pink and white lip.

The plant is Uncommon in Ontario, rare in Manitoba, the Ram's-Head Lady's-Slipper is a threatened plant species in many areas within its range, including Wisconsin, Michigan, and Saskatchewan.

The species is considered rare to extremely rare in all locations where it occurs[1]. More specifically, it is rare in Ontario[2] and rare in Manitoba. The Ram's-Head Lady's-Slipper is a threatened plant species other areas within its range, including Wisconsin, Minnesota, Michigan, and Saskatchewan. It is believed to be extirpated in Connecticut. This species has now been listed as an endangered species in Nova Scotia.[3]


Plants are found in coniferous forest in damp swamps and rockey slopes from elevations of 0 to 1000 meters.


The pH of the potting media should be around 6. This species has a very difficult establishing when transplanted because of heavy loss of roots. But when it establishes, it is easy to grow. Plant grows in shade.


Cypripedium arietinum plate.jpg

Common Names: Ram's-Head Lady's-Slipper


  1. Arietinum americanum L.C. Beck 1833
  2. Criosanthes arietina (R. Br. in W.T. Aiton) House
  3. Criosanthes borealis Raf. 1818; Cypripedium arietina House
  4. Cypripedium arietinum f. biflorum P.M.Br. 1995
    1. Blaney, S. and D. Mazerolle. 2007. Nova Scotia Provincial Status Report on Ram's-Head Lady Slipper (Cypripredium arietinum R. Br.). Nova Scotia Deparment of Natural Resources.
    2. Oldham, M.J., and S.R. Brinker. 2009. Rare Vascular Plants of Ontario, Fourth Edition. Natural Heritage Information Centre, Ontario Ministry of Natural Resources. Peterborough, Ontario. 188 pp.
    3. Species List[1]