Cypripedium arietinum Ait. f. - Ram's Head Lady's Slipper


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Cypripedium arietinum - (image 1 of 5)



Family: Orchidaceae


Apparently in some places this species occurs in moist acid soils in coniferous woods but in NY it is most common in limestone woods and northern white cedar swamps.




Quebec to Manitoba, south to MA, NY, MI, and MN.


Herbaceous perennial; stem slender, 10-40 cm, thinly hairy, with 2 or 3 sheathing scales below and 3-5 sessile leaves above the middle; leaf blades lanceolate to elliptic, often folded, 5-10 cm long, finely ciliate, otherwise glabrous; flowers solitary; sepals and lateral petals 1.5-2.5 cm, greenish-brown; upper sepal lanceolate, the lateral two separate, linear; lateral petals lance-linear, similar to the lateral sepals; lip whitish and usually strongly red-purple veined, 1.5-2.5 cm, prolonged downward into a conical pouch, the opening with numerous white hairs.      


Flowers late May to early June

Wetland indicator: FAC

Differs from other eastern North American lady's slippers in having the lower two sepals separate and spreading rather than fused together for most other their length. It is rare throughout its range.


Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. Second Ed.
The New York Botanical Garden. Bronx, NY




 Michael Hough 2018