Corallorhiza

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.

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.

Sep and lateral pet narrow, similar, usually spreading-ascending or projecting over the column; lateral sep united with the base of the column, often forming a low protuberance or short spur at the summit of the ovary; lip deflexed, oblong to rotund, often with 2 lateral lobes or teeth, the margins usually upturned, and the face bearing one or 2 short longitudinal ridges; column shorter than the perianth, rather broad or boat-shaped, slightly incurved, its terminal anther with 4 pollinia; fr pendulous; yellow, brown or purplish mycotrophic plants; stem arising from a cluster of coralloid roots, bearing a few sheathing scales and a terminal raceme of small, usually bicolored fls. 10, N. Amer.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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