Corallorhiza odontorhiza (Willd.) Nutt.

Late coral-root, autumn coral-root

The specific epithet odontorhiza is from the Greek meaning "tooth-root," in reference to the tooth-like swollen base of the stem.

DESCRIPTION: Plant glabrous, 10-20 cm tall, arising from a branched, coralloid rhizome. Base of the stem swollen into a tooth-like pseudobulb. Leaves reduced to several bladeless bracts sheathing the stem. Inflorescence a lax terminal raceme, 5-13 flowered; each flower subtended by a small, linear-lanceolate bract. Sepals linear-lanceolate, 3-4.5 mm long and 1-1.5 mm wide, madder-purple, typically green at the base. Petals oblanceolate, about 4 mm long and 1.5 mm wide, colored as sepals. Labellum clawed, obovate to orbicular; 2.5-4 mm long and 3-5 mm wide, the margin undulate or crenulate, the base of the central portion with two fleshy ridges, white spotted with dark purple. Flowers may be cleistogamous, in which case all flower parts are connivent. In chasmogamous flowers, the sepals and petals are loosely connivent and form a hood over the column.

Corallorhiza odontorhiza could possibly be confused with a late-flowering specimen of C. maculata, although C. odontorhiza typically blooms after C. maculata is done flowering. The two can be easily be separated by the shape of the labellum, which is undivided in C. odontorhiza, but is divided in three parts in C. maculata.

Corallorhiza odontorhiza can be found in a variety of forested upland habitats, although the woods it grows in are typically mesic, and only occasionally dry.

August 20-September 25.

The flowers of Corallorhiza maculata come in two forms: the typical cleistogamous form, and a less common chasmogamous form. While the cleistogamous form is self-pollinating, I am unsure whether this is the case for the chasmogamous form. It is possible that the chasmogamous form is insect-pollinated. A study of the pollination biology/breeding system of the chasmogamous form might hold some potential for increasing our understanding of the evolution of cleistogamy.

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