Orchis clavellata Michaux, Fl. Bor.-Amer. 2: 155. 1803; Habenaria clavellata (Michaux) Sprengel; H. clavellata var. ophioglossoides Fernald

Plants 8–47 cm. Leaves 1(–2), on basal half of stem, ascending to spreading, usually abruptly reduced to bracts distally; blade oblanceolate to oblong, linear-oblong, or elliptic, 3–19 × 0.8–3.5 cm. Spikes moderately dense. Flowers resupinate, often incompletely so and held at angle, not showy, rather inconspicuous pale green to dull yellowish green; lateral sepals porrect; petals ovate to obovate; lip oblong, obscurely 3-lobed, without basal thickening, 3–7 × 3–4 mm, margins sometimes dentate-lacerate, apex truncate; spur clavate, 7–13 mm; rostellum lobes directed downward, very short, truncate; pollinaria straight or slightly curved laterally; pollinia fragmenting, pollen masses trailing down onto stigma; viscidia linear to linear lanceolate; ovary rather stout, 6–11 mm. 2n = 42.

Flowering summer (Jun--Aug). Sphagnum bogs, sphagnous seeps and meadows, wet sandy and peaty meadows, marshes, low woods, wet prairies, and roadsides; 0--2000 m; N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que.; Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Ky., La., Maine, Md., Mass., Mich., Minn., Miss., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Tex., Vt., Va., W.Va., Wis.

In common with Platanthera nivea and P. integra, the column of P. clavellata bears a series of lateral projections that are directed forward; the upper pair is elaborately adorned and may be glandular. It appears that this species is inappropriately placed in Platanthera. See note under 30. P. nivea.

The broader leaves cited as distinguishing Platanthera clavellata var. ophioglossoides are more prevalent in the North, but occur throughout the range of the species. In some areas populations commonly display a complete range of leaf shape; this feature alone is of no taxonomic significance.

The unusual and infrequent hybrid Platanthera blephariglottis × P. clavellata is P. × vossii Case.