Green adder’s-mouth, malaxis unifolié

Malaxis ophioglossoides Muhlenberg ex Willdenow; M. thlaspiformis A. Richard & Galeotti; Microstylis grisebachiana Fawcett & Rendle

Plants 3–50 cm. Pseudobulbs 5–20 mm diam. Leaves 1(–2, rarely), near middle of stem; blade bright green, glossy, narrowly to broadly ovate, keeled abaxially, 1.6–10 × 0.5–5 cm, apex acute. Inflorescences racemes, appearing umbellate before elongation of rachis, 1–13 cm; floral bracts triangular, 0.16–1.4 mm; pedicels (3.8–)5–10(–13) mm. Flowers 10–160, resupinate, green; dorsal sepal oblong-elliptic, 1.1–1.9 (–2.2) × 0.5–1 mm, apex acuminate; lateral sepals oblong-elliptic, 1.1–1.9(–2.2) × 0.5–1 mm, apex acuminate; petals strongly recurved, linear to filiform, slightly falcate, 0.8–1.7(–3) × 0.1–0.2(–0.3) mm; lip rhombic-deltate to cordate-ovate or oblong-elliptic, 1.1–2.3 × 1–2.2 mm, base cordate or auriculate, auricles less than 0.6 times as long as distance from base of lip to apex of middle lobe, apex 3-dentate; column 0.4–0.6 × 0.4–0.6 mm; pollinia yellow. Capsules spreading to slightly drooping, subglobose to ellipsoid, 8 × 4 mm.

Flowering spring--fall (south--north). Swamps, bogs, sand barrens, heathlands, and dry woods; 0--600 m; Man., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que.; Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Tex., Vt., Va., W.Va., Wis.; Mexico; West Indies; n Central America.