Bracts: abaxial surface of distalmost sheathing bract (and often the next) densely and conspicuously silvery-pubescent when young (later sometimes glabrescent). Leaves 4-5, rather evenly spaced along stem, alternate, spreading; blade orbiculate to lance-elliptic to ovate or obovate, 9-19 × 2.5-9 cm. Flowers 1-2, small, scent moderate to faint, rose or musty; sepals and petals usually minutely but densely spotted with reddish brown or madder and appearing uniformly dark, rarely only coarsely spotted and blotched; lip oblance-ovoid to calceolate (slipper-shaped), 22-34 mm; orifice 12-19 mm. Flowering Apr--Jun. Mesic to dry deciduous and deciduous-hemlock forests, usually on slopes; mostly 0--1200 m; Ala., Ark., Conn., Del., Ga., Ill., Kans., Md., Mass., Mo., Nebr., N.J., N.Y., N.C., Ohio, Okla., R.I., Tenn., Va.
Smaller, with smaller, darker fls, the pet 3-5 cm, the lip 2-3 cm, chiefly of moist or wet low places, is northern and cordilleran, s. in our range to N. Engl., the Lake states, n. N.J., Pa., O., and at progressively higher elev. in the S. Appalachian Mts. to N.C. (C. parviflorum)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.