Skip to main content

U.S. Forest Service

Plant of the Week

Map of the United States showing states. States are colored green where the species may be found. Corallorhiza mertensiana range map. USDA PLANTS Database.

Merten’s coralroot orchid. There is an innate subtle beauty to Merten’s coralroot orchid. Like many species in the genus, Corallorhiza the expression of the anthocyanin pigments varies from one individual or population to another. In this image Merten’s coralroot is a beautiful lavender color. Image with permission by Rod Gilbert.

Close-up of an individual flower. In this close-up of an individual flower, note that the three sepals are adjacent to one another and slightly recurved over the column while the two lateral petals and lip are spreading. Image with permission by Tom Nelson.

Merten’s coralroot orchid that contains no anthocyanin pigments thus yielding a creamy yellow coloration. In this image, we observe a Merten’s coralroot orchid that contains no anthocyanin pigments thus yielding a creamy yellow coloration. Image with permission by Raymond Prothero.

Merten's Coralroot (Corallorhiza mertensiana)

By Larry Stritch

Merten's coralroot orchid is a herbaceous, perennial wildflower with a contiguous distribution in the northwestern United States north into British Columbia and adjacent Alberta and then into southeast Alaska, with several disjunct populations in Montana and Wyoming. Merten's coralroot orchid occurs occasionally as a single aboveground flowering scape or as an occurrence with numerous scapes.

Corallorhiza mertensiana (Corallorhiza: corallion, coral and rhiza – root; coralroot and mertensiana, for botanist Carl Franz Mertens) refers to the underground stems, rhizomes, appearing like an ocean coral.

Corallorhiza mertensiana attains a height of 30 to 65 centimeters. The lavender purple to reddish -purple scape emerges from a small coral-shaped rhizome. The leaves are reduced to sheaths surrounding a simple scape (stalk of the inflorescence), pale red to lavender purple to reddish-purple. Occasionally, there are individual flowering scapes or an entire population is creamy yellow because the anthocyanins (flavenoid pigments) which give this orchid its pale red to lavender purple to reddish-purple are absent. The inflorescence is a lax to dense raceme of few to numerous flowers. Flowers range from fully open and spreading to converging but not closed. The flowers are variously colored, usually reddish to purplish or lavender purple, with the petals commonly spotted with purple, the lip is generally white. The fruit is a capsule.

Corallorhiza mertensiana flowers from late spring to summer. The species occurs in a broad array of coniferous to deciduous habitats in humus rich soils.

For More Information