Orthotrichum coarctatum P. Beauvois, Prodr. Aethéogam., 80. 1805; O. ludwigii Bridel; Ulota ludwigii (Bridel) Bridel

Plants 0.5-1.5 cm. Stems erect. Stem leaves slightly twisted, erect-curved when dry, narrowly lanceolate to lanceolate, 1.5-2.5 mm; base ovate or oblong; margins reflexed; apex acute; basal laminal cells elongate-linear; distal cells 8-11 µm, papillae conic, small, or sometimes surface almost smooth. Specialized asexual reproduction absent. Sexual condition autoicous; perichaetial leaves little different from stem leaves. Seta 1.5-4 mm. Capsule obovate to oblong-obovoid, 1.1-2.8 mm, puckered and slightly 8-plicate at mouth, or smooth, mouth small, distinctly smaller than mid capsule; stomata in neck; peristome single; exostome teeth split to 16, erect, flexuose, densely and obscurely papillose; endostome segments absent. Calyptra oblong-conic, very hairy. Spores 19-26 µm.

Trunks, branches of deciduous trees, conifers; low elevations; N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que.; Conn., Idaho, Maine, Md., Mass., Mich., N.H., N.J., N.Y., N.C., Pa., Tenn., Vt., Va., W.Va., Wis.; Europe; Asia.

Ulota coarctata, a rather uncommon species, prefers climax beech-maple forests, and is distributed from Newfoundland south along the Appalachians to North Carolina and eastern Tennessee, westward in the Great Lakes region to Wisconsin. A disjunct specimen in northern Idaho (Leiberg s.n., US) is correctly identified, but the location needs to be verified. The obovoid capsules with strongly puckered mouth are diagnostic for this species. Ulota drummondii has football-shaped capsules, whereas U. crispa has oblong, 8-ribbed capsules constricted below the mouth. Additionally, U. coarctata has non-crisped leaves with clasping bases and acute apices.