Stems with epidermal cells smooth. Stem leaves 0.6-1 mm; alar cells small, subquadrate; distal laminal cells curved. Seta0.5-1.5 cm. Capsule 1-2.5 mm, smooth; peristome diplolepidous; exostome teeth 16, lanceolate, short; endostome segments 16, linear, stout. Spores 11-13 µm.

Mesic, rock shelves in montane forests, acidic rock; low to high elevations; Greenland; Alta., B.C., N.B., Nfld. and Labr., N.W.T., N.S., Ont., P.E.I., Que., Yukon; Alaska, Calif., Colo., Idaho, Maine, Mass., Mich., Minn., Mont., N.H., N.Y., N.C., Oreg., Pa., S.Dak., Tenn., Vt., Va., Wash., W.Va., Wis., Wyo.; West Indies; Central America; Europe; Asia.

Pterigynandrum filiforme is characterized by its slender, sleek, braided stems trailing down the sides of acidic rock. The somewhat curved, ovate, rather blunt leaves, and rhombic, coarsely prorulose laminal cells are additional identifying features.