Plants large, in loose or dense tufts. Stems creeping, sympodial, stipe erect, secondary stems erect, usually dendroid, 1 (or 2)-pinnate, branches terete-foliate, attenuate-caudate distally; hyalodermis absent, sclerodermis of 1 or 2 rows of cells, central strand present; paraphyllia many, hyaline, 1-seriate; loosely tomentose, rhizoids red. Primary stem leaves appressed, scalelike. Distal stem and branch leaves oblong-ovate to ovate-lanceolate; base narrowly decurrent; margins entire to serrulate proximally, toothed distally; apex acute to obtuse and apiculate; costa single, subpercurrent, smooth; alar cells subquadrate; laminal cells 1-stratose, smooth; proximal cells oblong-rhombic to linear-rhomboidal; medial cells linear-elongate, rhomboidal to subquadrate; apical cells rectangular to rounded-fusiform, walls thin or slightly thickened. Specialized asexual reproduction absent. Sexual condition dioicous; inflorescences on secondary stems and bases of branches. Seta single, elongate, straight, smooth. Capsule erect, symmetric; differentiated annulus absent; operculum conic-acute to subrostrate; peristome double; exostome teeth 16, connate at base, dark red-brown, linear-lanceolate, somewhat trabeculate, external surface minutely and densely papillose, bordered, minutely and irregularly perforate; endostome golden brown, basal membrane low, segments well developed, linear, as long as teeth, keeled, minutely and densely papillose, split along median line or gaping, ultimately split to apex, cilia absent or rudimentary. Calyptra cucullate, smooth, reaching capsule base. Spores (12-)15-22 µm, minutely papillose, yellowish brown.
SELECTED REFERENCES Horton, D. G. and D. H. Vitt. 1976. Morphological characters, relative to distribution, and taxonomic considerations of the genus Climacium in North America. Canad. J. Bot. 54: 1872-1883. Noguchi, A. 1952b. Mosses of Climaciaceae. Res. Bull. Fac. Liberal Arts Oita Univ., Nat. Sci. 1: 65-77. Shaw, A. J. et al. 2012. Climacium (Climaciaceae): Species relationships and biogeographic implications. Bryologist 115: 23-30. Shaw, A. J., M. S. Gutkin, and B. R. Bernstein. 1994. Systematics of tree mosses (Climacium: Musci): Genetic and morphological evidence. Syst. Bot. 19: 263-272.