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.

Perennial mycotrophic (saprophytic) herb 10 - 46 cm tall

Leaves: none.

Inflorescence: a single, erect, usually under 25 cm tall, terminal, long-stalked, loose, narrow (1 - 2.5 cm wide), spike-like cluster of five to thirty, slender-stalked, inconspicuous flowers with each flower subtended by a minute bract.

Flowers: dark brownish purple to more reddish purple, small (3 - 5 mm long), bilaterally symmetric, lacking a spur, but with sepals and petals grouped together and pointing forward to form a hood over lip petal. The reproductive parts of stamens, stigma and style are fused into a column above the 2.5 - 5 mm long, inferior ovary.

Sepals: three, forward-pointing, petal-like, dark purple-brown or reddish purple, with central sepal 3 - 4 mm long and 1 - 1.5 mm wide while lateral sepals somewhat narrower (about 1 mm wide) and a bit longer (3 - 5 mm long). The upper sepal has a single prominent lengthwise vein and is fairly lance-shaped with a blunt tip, but the lateral sepals are more linear.

Petals: three, with upper two pointing forward and converging with upper sepal to form a hood over lip petal. The two lateral petals are 3 - 4 mm long, about 1 mm wide, inversely egg- to spoon-shaped, and greenish purple to brown. Lip white with purple to magenta streaks or spots, unlobed, rounded with narrowed base, and irregular fringe along tip edges. The main surface of the lip petal also has two divergent lengthwise ridges (lamellae) near the base.

Fruit: several, stalked, nodding, 5.5 - 8 mm long, 3.5 - 5 mm wide, plump, rounded to ellipsoid capsules with remnant column at apex.

Flowering stem: single, erect, strongly thickened and bulbous at base, hairless, fleshy, brownish to purple or yellow to greenish, lacking leaves, but with a few tubular sheaths. This leafless structure terminated by flowers is called a scape and technically is not a true stem.

Root system: lacking true roots, but with multiple-branched, coral-like rhizome with swollen area meeting stem base.

Column: white at base and often purple toward tip, 1.8 - 2.4 mm long, 0.8 - 1.7 mm wide, with two distinct ear-shaped appendages on upper surface near base. The relatively large (0.3 - 0.5 mm long, 0.7 - 1 mm wide) stigmatic surface is broad and oblong.

Similar species: Corallorhiza odontorhiza var. pringlei is most similar to the typical C. odontorhiza var. odontorhiza, but that variety usually has closed flowers (cleistogamous); a narrower (1.7 - 2.5 mm wide) and slightly shorter (2 - 4 mm long) smooth-tipped lip petal; a 1.9 - 2.5 mm long, 0.8 - 1 mm wide column lacking appendages at the base; and a smaller (0.2 - 0.4 mm long, 0.3 - 0.5 mm wide) stigmatic surface. Possibly confused with C. wisteriana, that species has a larger central sepal (over 4.5 mm long) with three veins, and it flowers much earlier in the year (April to June).

Flowering: September

Habitat and ecology: Very rare, presumably in deciduous woods and mixed woods, but only verified in our area from two specimens, one from Berrien Co., MI and the other from Walworth Co., WI.

Occurence in the Chicago region: native

Notes: This variety of Corallorhiza odontorhiza has a spotty distribution in the United States and Canada, and mostly overlaps the northern edge of the range of the species. Unlike the typical variety, the flowers do not self-pollinate and research has shown that characteristics of the column would make self-pollination difficult (Freudenstein 1997).

Etymology: Corallorhiza comes from the Greek words korallion, meaning coral, and rhiza, meaning root, in reference to the branching, underground rhizome, which has a similar appearance to coral. Odontorhiza means "toothed root" in reference to the tooth-like swelling of the stem base above the rhizome. Pringlei is named in honor of the American botanist C. G. Pringle (1838 - 1911), who worked in the U.S., Mexico, and Cuba.

Author: The Field Museum