Cypripedium arietinum
R. Brown
Ram's Head Lady's Slipper

Location Nova Scotia, Quebec, Ontario, Manitoba, and Saskatchewan. In Ontario, mainly a Great Lakes - St. Lawrence orchid of the Mixed Forest Region.
Specific Habitat

Two different types of habitat: one dry to moist, the other moist to wet. The first is provided by maturing coniferous forests in areas of thin soil or sand dunes over flat-lying calcareous rocks. Plants grow in dappled to partial shade of openings in the forest canopy.
Moist to wet conditions of coniferous fens and edges of cedar swamps sometimes drown plants in rising water levels.

Flowering Season

Last 10 days of May to mid. June.


Height 10-50 cm. Stem slender and hairy.
Leaves 3-4, deep green, elliptical, strongly ribbed, arranged in a rough spiral about the stem.
Flowers solitary, scape to 15 cm. Petals and sepals greenish-brown, linear. Lip is white crisscrossed with dark red veins, sometimes veins are faint. Lip is prolonged downward into a small conical pouch. Mouth of lip covered with white hairs . Opening circular.


Blooms a little ahead of other Cypripediums in areas where it occurs. Most common on Bruce Peninsula and Manitoulin Island in Ontario. Some locations in the Bruce Peninsula and Ottawa District are known to have provided stable habitats for this genus for many decades. Plants develop rapidly after appearing above ground, and blossom is rather short-lived. Pollination of a bloom creates a hormone reaction within an hour, causing the upper sepal to drop down and seal the lip. Requires cool soil conditions.


Orchids of Ontario
Orchids of the Western Grest Lakes
The Canadian Field-Naturalist Vol. III - 1
The Orchids of Bruce & Grey


© Royal Botanical Gardens, Dr. Donald Gunn Image Collection.