Plants 35-110 cm. Flowers: lip 9-26 × 4-9 mm; spur 30(-48)-50 mm, slenderly cylindric to commonly somewhat clavate; ovary 18-31 mm.
Flowering Aug--Sep. Moist to wet sandy and peaty meadows, marshes, pine savannas, open woods; 0--400 m; Ala., Fla., Ga., Miss., N.C., S.C., Tex.
The widespread Platanthera blephariglottis var. blephariglottis tends to have a dense inflorescence of smaller flowers with the descending to reflexed lips rather simply fringed (in extreme cases scarcely more than deeply lacerate). In contrast, the typically open, lax inflorescence of var. conspicua bears larger flowers often with an exquisitely elaborate filiform fringe on the porrect lips. Although typical plants of the two varieties are quite distinctive, most characters vary considerably within and between the varieties and can be misleading. In contrast, spur length seems to be unambiguous, and insofar as it reflects specialization for different pollinators, upon further study it may be shown to delimit distinct species. Additionally, in the limited area in which the two varieties occur together, var. conspicua may bloom somewhat later than var. blephariglottis.
Hybrids of Platanthera blephariglottis with P. ciliaris are P. × bicolor (Rafinesque) Luer and with P. cristata are P. × canbyi (Ames) Luer. The unusual and rare hybrid P. blephariglottis × P. clavellata is P. × vossii Case.