Corallorhiza odontorhiza - Autumn Color Root

The autumn coral-root orchid is an herbaceous, perennial wildflower with a broad distribution across the eastern United States into southern Ontario and Quebec provinces, Canada, with several disjunct populations in Louisiana, Florida, South Dakota, Oklahoma, and New Mexico Autumn coral-root occurs occasionally as a single aboveground flowering scape or as several scapes in a clone.

Corallorhiza odontorhiza
Corallorhiza odontorhiza. Image permission by Rod Gilbert.

USDA NRCS PLANTS Database range map for the species.
Corallorhiza odontorhiza range map. USDA PLANTS Database.

Corallorhiza odontorhiza (Corallorhiza – corallion – coral and rhiza – root; coral-root and odontorhiza odontos – tooth and rhiza – root; toothed-root) refers to the underground stems, rhizomes, appearing like an ocean coral and the tooth-like swollen base of the scape.

Corallorhiza odontorhiza attains a height of 10 to 30 centimeters. The yellow-green to purplish-brown scape emerges from a small, bulbous coralloid rhizome. The leaves are reduced to sheaths surrounding a simple scape (stalk of the inflorescence), yellow-green to purplish-brown at least midway up the scape. The inflorescence is a lax raceme of few to numerous flowers. Flowers range from open and slightly spreading to converging and nearly closed. The flowers are generally reddish-purple to reddish-brown often with a greenish caste, the perianth nearly closed in the cleistogamous flower and the perianth open in the chasmogamous flower; the lip is white, usually purple-spotted. There is a yellow color morph sometimes referred to as forma flavida. The fruit is a capsule.

Corallorhiza odontorhiza
Corallorhiza odontorhiza. Image permission by Jim Fowler.

Corallorhiza odontorhiza
Corallorhiza odontorhiza. Image permission by Diane Peirce.

Corallorhiza odontorhiza
Corallorhiza odontorhiza. Cleistogamous flower. Image permission by Charles Peirce.

Corallorhiza odontorhiza
Corallorhiza odontorhiza. Chasmogamous flower. Image permission by Diane Peirce.

Taxonomic note: Magrath and Freudenstein in the Flora of North America recognize two geographically overlapping varieties: Corallorhiza odontorhiza var. odontorhiza and C. odontorhiza var. pringlei.

Corallorhiza odontorhiza flowers from late summer to early autumn. The species occurs in a broad array of deciduous or mixed coniferous/deciduous forest habitats in humus rich soils.

Special note: The two forms of flowers can occur in close proximity to one another. Also, yellow-green to green color variants of Corallorhiza odontorhiza are occasionally misidentified as Corallorhiza trifida where their ranges overlap.

Corallorhiza striata