Flowers: perianth open; lip similar to petals (narrowly obovate-spatulate), 2.7-4.6 × 2-3.7 mm; column 1.8-2.4 × 0.8-1.7 mm, base with 2 prominent auricles on adaxial surface; stigmatic surface 0.3-0.5 × 0.7-1 mm. Flowering late summer--fall. Rich deciduous woods, mixed woods, and conifer plantations; 0--2800 m; Ont.; Conn., Ga., Ind., Iowa, Mich., N.J., N.Y., N.C., Pa., Tenn., Wis.; Mexico; Central America (El Salvador, Guatemala, Honduras, Nicaragua). In Corallorhiza odontorhiza both chasmogamous and cleistogamous flowers exist; they occur on separate plants, although sometimes in the same populations. The cleistogamous form is by far the more frequent.