Listera

Herbs, perennial, terrestrial. Roots slender, fibrous. Stems slender to stout, glabrous proximal to leaves; cauline bracts 2(-3), enclosing base of stem. Leaves 2(-3, rarely), at apex of stem, opposite or subopposite, sessile, glabrous. Inflorescences terminal, 2-100-flowered racemes; peduncle and rachis densely glandular-pubescent or glabrate; floral bracts inconspicuous, lanceolate, elliptic, suborbiculate-ovate, rhombic-ovate, or oblong. Flowers resupinate, maroon-purple, yellowish green to dark green, blue-green, or pinkish tan; dorsal sepal ovate-elliptic, elliptic-obovate, linear-elliptic, or lanceolate; lateral sepals semiorbiculate-elliptic, ovate, linear-elliptic, or oblong-lanceolate, often falcate-recurved; petals reflexed, spreading, or connivent, linear, linear-oblong to lanceolate, or elliptic, falcate; lip prominently deflexed or not, sessile or clawed, linear-oblong to obovate, suborbiculate-ovate, or ovate-reniform, base of lip with or without prominent auricles or lobes, apex deeply 2-lobed, dilated to rounded, apiculate; calli various, papillose, pair of horns, or with 1-2 lamellae; column arcuate, thick, short, apex expanded or not; anther on adaxial side of column near apex; pollinia 2, yellow, soft; ovaries pedicellate. Fruits capsules, horizontal to semierect, ellipsoid, ovoid, or subglobose, glabrous or glabrate to glandular-pubescent.

Sep and lateral pet much alike, spreading or reflexed; lip declined or projecting horizontally, in our spp. much longer than the lateral pet, 2-lobed or 2-cleft; column erect, shorter than the pet, the anther borne on its back near the tip; pollinia 2; stem bearing a single pair of broad, opposite, sessile lvs near its middle and a terminal raceme of small, green to purple or red fls; our spp. glabrous below the lvs, ±pubescent above them. 25, N. Hemis.

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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