56. Corallorhiza Gagnebin, Acta Helv. Phys.-Math. 2: 61. 1755; orthography conserved.
Coral-root, corallorhize [Greek korallion, coral, and rhiza, root, referring to coral-like appearance of branching, underground rhizome]
Lawrence K. Magrath & John V. Freudenstein
Cladorhiza Rafinesque; Corallorhiza Châtelain; Rhizocorallon Gagnebin
Herbs, perennial, solitary or colonial, mycotrophic, rootless, leafless. Stems erect, yellowish green or brown to purple, glabrous; sheathing bracts few, reduced. Rhizomes branching, coralloid; scales minute. Inflorescences laxly to densely flowered racemes, subtended by 3–4 tubular bracts reduced to closed sheaths, glabrous. Flowers 2–41, inconspicuous to showy; perianth spreading to closed; sepals and petals lanceolate to oblanceolate, apices acute to nearly obtuse; lip broadly obovate, with 2 basal lamellae, often with 2 lateral lobes, narrowed to claw; column curved toward lip, with or without basal auricles; anther incumbent, operculate; pollinia 4, superimposed, yellow, unequal; rostellum triangular; stipe narrowly triangular; ovary narrowly ellipsoid-obovoid, often with small mentum adaxially at distal end. Fruits capsules, pendent, ellipsoid to slightly obovoid, 3-ribbed. Seeds cylindric-fusiform. x = 20, 21.
Species 11 (7 in the flora): mostly temperate regions, North America, Central America, 1 circumboreal.
Sporadically occurring color forms are known in all Corallorhiza species in the flora, and they range from plants with unspotted petals to completely yellow plants, apparently devoid of anthocyanin. Various genera of fungi are known to be associated with Corallorhiza.
Freudenstein, J. V. 1997. A monograph of Corallorhiza (Orchidaceae). Harvard Pap. Bot. 1(10): 5–51.