Plants 5-33 cm. Stems green to reddish purple, succulent, glabrous. Leaves: blade broadly to narrowly ovate-cordate or deltate, 0.9-2(-4) × 0.7-2(-3.8) cm, apex mucronate. Inflorescences 5-25-flowered, lax to dense, 20-100 mm, slender; floral bracts ovate, 1-1.5 × 1 mm; peduncle and rachis slightly glandular-puberulent or glabrate; bracts, pedicel, and ovary glabrous. Flowers yellow-green, green, or reddish purple; pedicel slender, 2-3 mm; dorsal sepal ovate-oblong to oblong-elliptic, 2-3 × 1 mm, apex obtuse; lateral sepals ovate-oblong to oblong-elliptic, slightly falcate, 2-3 × 0.5-1.5 mm, apex obtuse; petals elliptic to oblong-linear, 1.5-2.5 × 0.5-1 mm, apex obtuse; lip linear-oblong, cleft 1/2 -2/3 its length into 2 linear-lanceolate lobes, 3-4 × 1-1.5 mm; disc with pair of spreading, linear lobes, apices acute; column 0.5 × 0.5 mm. Capsules semierect, subglobose, 5 × 4 mm.

Listera cordata is the most widespread species in the genus.

Leaves: blade 0.9-2 × 0.7-2 cm. Flowers yellow-green, green, or reddish purple; pedicels 2 m; sepals 2-3 × 0.5-1.5 mm; petals 1.5-2.5 × 0.5-1 mm; lip 3-4 × 1-1.5 mm. 2n = 36, 38, 40, 42.

Flowering late May--Aug. Mountainous regions in mossy, damp, coniferous or mixed coniferous-hardwood forests, sphagnum bogs and evergreen swamps, and subacid humus in moist woodlands; 0--1200 m; Greenland; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Conn., D.C., Maine, Md., Mass., Mich., Minn., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., Vt., Va., W.Va., Wis.; Europe; Asia (Japan); Iceland.

Leaves: blade 2-4 × 1.8-3.8 cm. Flowers green to yellow-green; pedicels slender, 3 mm; sepals 4 × 1.5 mm; petals 1.5-2.5 × 0.5-1 mm; lip 5-6 × 1-1.5 mm. 2n = 36, 38

Flowering Jun--Jul. Shaded humus of rich, well-drained, coniferous or coniferous-hardwood forest; 1500--3500 m; Alta., B.C., N.W.T., Yukon; Alaska, Calif., Colo., Idaho, Mont., N.Mex., Oreg., Wash., Wyo.

Taxonomists have differed about whether these two varieties deserve to be recognized. The arguments for maintaining the varieties as distinct (C. A. Luer 1975) and against maintaining them as distinct (D. S. Correll 1950; C. L. Hitchcock et al. 1955-1969, vol. 5; J. A. Calder and R. L. Taylor 1968; E. Hultén 1941-1950, vol. 3) have been summarized (R. A. Coleman 1995). Although leaf size and shape overlap, the leaves of the western plants are broader than long, those of the eastern plants longer than broad. Nonetheless, the distinction is not sufficient to maintain separate varieties (J. A. Calder and R. L. Taylor 1968). In the present treatment we have taken a conservative approach and include the two varieties. We recognize, however, that in North America, Listera cordata is a highly variable species: although some plants easily fit one or the other of the described varieties, a host of intermediates do not fit either. Further study of this species 'complex' is needed.

Stems 1-2.5 dm; lvs 1-3 cm, shorter than the peduncle, truncate or subcordate at base, but also abruptly contracted at the point of insertion; axis, pedicels, and ovary glabrous; bracts minute, 1 mm; fls up to ca 25, green to purple or red; sep and lateral pet 2-2.5 mm, ovate oblong; lip 3-5 mm, with 2 projecting lateral teeth near the base, cleft to the middle or below into divergent linear lobes; column 0.5 mm. Deep wet woods and sphagnum-bogs; circumboreal, s. in Amer. to N.Y., Pa., Mich., and Minn., and in the mts. to N.C. and N.M. June, July. (Ophrys c.)

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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