This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Acaulescent herbs, with fleshy-fibrous roots and glandular-pubescent foliage. Leaves 2, basal; blades ample, plaited, spreading. Scape simple. Flower usually solitary. Perianth irregular. Sepals greenish, narrowed upward. Lateral petals about as long as the sepals, linear, greenish. Lip a large drooping inflated sac with a closed fissure down its whole length in front. Column declined, glandular-pubescent, bearing a sessile anther on each side, and a rhomboidal glandular-pubescent sterile stamen above. Stamens spreading, the free tips at right angles to the column. Pollen granular, without glands or tails. Stigma broadest at the apex. Capsule ascending. [Latin, in allusion to the cleft lip.] A monotypic genus of eastern North America.
Cypripedium acaule Ait. Hort. Kew. 3: 303. 1789. Fissipes acaulis Small, Fl. SE. U. S. 311. 1903.
Scape 6'-15' high, rather stout. Leaves 2, basal, elliptic, 6'-8' long, 2-3' wide, thick; occasionally a smaller leaf is borne on the scape; sepals greenish purple, spreading, 1 1/2'-2' long, lanceolate, the 2 lateral ones united; petals narrower and somewhat longer than the sepals; lip often over 2' long, somewhat obo-void, folded inwardly above, pink with darker veins or sometimes white, the upper part of its interior surface crested with long white hairs; sterile stamen triangular, acuminate, keeled inside.
In sandy or rocky woods, Newfoundland to Manitoba, south to North Carolina, Tennessee and Minnesota. Ascends to 4500 ft. in Virginia. The hairs on the lower part of the bract and on the base of the ovary are often tipped with scarlet glands. Flower fragrant. Pink or purple ladies'-slipper. Nerve-root. Noah's-ark. Camel's-foot. Squirrel's-shoes. Two-lips. Indian-moccasin. Old-goose. May-June.