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U.S. Forest Service

The Slipper Orchids

Cypripedium arietinum: Ram’s-head lady’s slipper

The ram’s-head lady’s slipper occurs from central and eastern Canada through the great lakes region of the north central and northeastern United States.

the ram’s-head lady’s slipper.Photo by Susan Trull.

Map of the range of Cypripedium arietinum in North America.Courtesy of Flora of North America.

Cypripedium arietinum is a small plant with usually 3, but up to 5, leaves per stem. The species is distinguished by the single flower on each flowering stem having divided lateral sepals and a distinctive pouch shaped like an inverted, hairy, conical hat covered with crimson varicose venation and white at the lip.

The plants grow in cool, moist woodlands and coniferous forests among tamaracks and spruce or cedar with a preference for moist, mossy bogs. However, it also can be found in shady roadside ditches.

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Cypripedium arietinum in its habitat. Photo by Susan Trull.