Skip to main content

U.S. Forest Service

Plant of the Week

USDA Plants distribution map for the species. Corallorhiza odontorhiza range map. USDA PLANTS Database.

Corallorhiza odontorhiza. Autumn Coral-Root Orchid (Corallorhiza odontorhiza) orchid note the expanding ovary on the bottommost flower. In plants in which the flower is closed (cleistogamous) the flower is self-pollinating and the capsules begin developing as soon as the scape emerges from the ground. Image with permission by Jim Fowler.

Corallorhiza odontorhiza. Autumn Coral-Root Orchid (Corallorhiza odontorhiza) In plants in which the flower is open (chasmogamous) the lip is white with purple spots. The open-flowered autumn coral-root orchid is much less frequent than the closed-flowered autumn coral-root orchid. Image permission by Chuck Peirce.

Corallorhiza odontorhiza. Autumn Coral-Root Orchid (Corallorhiza odontorhiza) developing capsules of this pair of close-flowered (cleistogamous) autumn coral-root orchids. Image with permission by Diane Peirce.

Autumn Coral-Root (Corallorhiza odontorhiza)

By Larry Stritch

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: “corallion” = coral and “rhiza” = root; and odontorhiza: “odontos” = tooth and “rhiza” = 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. 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 totally yellow color morph sometimes referred to as forma flavida. The fruit is a capsule.

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.

For More Information