Plants small to large, in loose to dense tufts or mats, light or deep green, yellowish, brownish, stramineous, whitish, or rarely blackish, usually glossy. Stems creeping, ascending, erect, arching, or pendent, green or reddish, densely to loosely terete-foliate, rarely subcomplanate-foliate, irregularly or regularly pinnate, branches usually straight to curved, terete-, subcomplanate-, or complanate-foliate, sympodial branching common; hyalodermis absent, central strand usually present; paraphyllia absent; pseudoparaphyllia acute to acuminate, first leaf pointed downward, second and third situated at 120± from first; rhizoids on stem below leaf insertion or along zone of contact with substrate in creeping stems; axillary hairs of 2-7 cells. Stem leaves appressed, erect, spreading, patent, or falcate-secund, loosely to closely imbricate, rarely well spaced, linear-lanceolate, broadly ovate, or broadly triangular, strongly longitudinally plicate to not plicate; base slightly narrowed or rounded to insertion, short to long and narrowly to broadly decurrent; margins plane to recurved, serrate, serrulate, or entire; apex gradually tapered or acuminate, occasionally piliferous from rounded-cucullate base; costa to (20-)40-100% leaf length, terminal spine present or absent, abaxial surface occasionally toothed; alar cells usually differentiated, larger or smaller than basal laminal cells, region more pellucid or more opaque, usually specific to particular species; laminal cells usually elongate to linear, 6-15:1, occasionally 20:1 or 1.5-5:1, smooth or strongly prorate in distal ends, walls thin to moderately thick, rarely as thick as lumen; basal juxtacostal cells usually shorter, wider than more distal cells, walls usually more incrassate, region more opaque or more pellucid, sometimes undifferentiated. Branch leaves usually smaller, relatively narrower; base more short-decurrent; margins usually more strongly serrate; apex more gradually acute or acuminate; costa usually relatively longer, more often projecting in relatively stronger spine; laminal cells shorter, same width as in stem leaves or rarely narrower; basal cells often not patterned as those of stem leaves, areolation more even across base, cells wider. Specialized asexual reproduction absent. Sexual condition autoicous, dioicous, phyllodioicous, or rarely synoicous; perichaetial leaves in species with horizontal capsules reflexed, base sheathing, apex gradually or abruptly acuminate, costa barely discernible or weak and short, to 1/2 base length, rarely long and vanishing in acumen; perichaetial leaves in species with erect capsules usually straight. Seta red-brown, usually dark red-brown with age, rarely cherry red or orangish, usually long (5-20 times capsule urn length) (short in Zelometeorium), twisted, rough or smooth. Capsule usually horizontal, sometimes erect, color similar to seta; annulus not separating or 404 separating by fragments; operculum conic or rostrate; peristome xerocastique or hygrocastique, perfect, exostome teeth cross striolate proximally; endostome conspicuous, not adherent to exostome (except in Homalotheciella), basal membrane 1/3-1/2 endostome length, segments broad, cilia 2 or 3, sometimes modified (for example, exostome teeth papillose to base, endostome basal membrane less than 1/3 endostome height, cilia reduced or absent, etc.) in association with erect capsules and usually hygrocastique peristome. Calyptra cucullate (mitrate in Zelometeorium), naked, rarely hairy. Spores 9-28 µm.
SELECTED REFERENCES Huttunen, S., A. A. Gardiner, and M. S. Ignatov. 2006. Advances in knowledge of the Brachytheciaceae (Bryophyta). In: A. E. Newton and R. S. Tangney, eds. 2006. Pleurocarpous Mosses: Systematics and Evolution. Boca Raton. Pp. 117-143. Huttunen, S. and M. S. Ignatov. 2004. Phylogeny of Brachytheciaceae (Bryophyta) based on morphology and sequence level data. Cladistics 20: 151-183. Ignatov, M. S. and S. Huttunen. 2002. Brachytheciaceae (Bryophyta))—a family of sibling genera. Arctoa 11: 245-296. Robinson, H. 1962. Generic revisions of North American Brachytheciaceae. Bryologist 65: 73-146.