Stems 20–230 cm. Leaves: petiole (0–)2–10(–20) mm; blade broadly elliptic to narrowly elliptic, 17–230 × 6–54 mm, base cuneate, margins once-serrate, teeth 1–6 per cm, abaxial surface glabrous or pilose, rarely tomentose, adaxial glabrate or mostly glabrous. Cymes 30–115 mm; bracts 4–23 × 3–10 mm, ape× acute to acuminate, rarely obtuse. Flowers: caly× lobes 5–11 × 3–8 mm, margins not or sparsely, rarely densely, ciliate; corolla completely white to white in tube and distally green-white, pink, red, or purple, tube 13–20 mm, abaxial lobes 6–16 × 5–15 mm, adaxial slightly keeled; palate white-bearded, rarely green-yellow-bearded; adaxial filaments (10–)15–24 mm; staminode 4–12(–16) mm, ape× green; style 15–30 mm. 2n = 28.
Phenology: Flowering Jul–Nov.
Habitat: Bogs, fens, marshes, swamps, seeps, stream banks, wet meadows and woods, margins of ponds and lakes.
Elevation: 0–2000 m.
St. Pierre and Miquelon, Man., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que., Ala., Ark., Conn., Del., D.C., Ga., Ill., Ind., Iowa, Ky., Maine, Md., Mass., Mich., Minn., Miss., Mo., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., S.C., Tenn., Vt., Va., W.Va., Wis.
A tetraploid population reported for Chelone glabra (T. S. Cooperrider 1970) likely is based on a misidentified specimen of C. obliqua var. erwiniae.
Chelone glabra has been proposed as a diploid progenitor for the allopolyploid C. obliqua (A. D. Nelson 1995; Nelson and W. J. Elisens 1999).
Infraspecific variants of Chelone glabra as proposed by F. W. Pennell (1935) are not recognized here because morphological variation within and among populations appears to be independent of geography. Qualitative and quantitative characters used to distinguish varieties have been shown to be highly variable; recognition of varieties is unwarranted (A. D. Nelson 1995; Nelson and W. J. Elisens 1999).
Chelone glabra in central Maine is visited exclusively by two species of bumblebees (Bombus fervidus and B. vagans) (B. Heinrich 1975). American Indians and pioneers used C. glabra as a tonic, laxative, and treatment for jaundice and internal parasites, and as an ointment to relieve itching and inflammation (C. S. Rafinesque 1828[–1830]); it is also used as an ornamental in bog gardens.