Green Adder's Mouth Orchid

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.

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.

Flowering spring--fall (south--north).

Swamps, bogs, sand barrens, heathlands, and dry woods; 0--600m.

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

Malaxis unifolia in southern Cumberlands

Malaxis unifolia, or the green adder's-mouth orchid, is a species of orchid occurring from eastern and central Canada (Newfoundland to Manitoba), the central and eastern United States (Maine to Florida, west as far as Minnesota, eastern Kansas, and eastern Texas), Mexico, Central America and the Greater Antilles (Cuba, Jamaica, Dominican Republic).

Malaxis unifolia generally has only one leaf, but rarely two. Flowers are green, in a raceme, often resembling an umbel at first before it elongates.