Plants small to large, in loose to dense mats, light to dark green, sometimes whitish, yellowish, or brownish, pale stramineous to yellow-brown with age. Stems creeping, ascending, erect, or arching, , densely to loosely terete-foliate, rarely subcomplanate-foliate or julaceous, irregularly or sometimes regularly pinnate, branches terete-, subcomplanate-, or complanate-foliate; central strand present; pseudoparaphyllia acute to acuminate; axillary hairs of 2-4 cells, . Stem leaves appressed, erect, spreading, patent, or falcate-secund, loosely or tightly imbricate, rarely somewhat spaced, lanceolate, ovate, or triangular, slightly to strongly concave, strongly to weakly longitudinally plicate, or plicae irregular, appearing crumpled, or not plicate; base narrowly to broadly short- to long-decurrent; margins serrate, serrulate, or entire, ; apex abruptly or gradually tapered or acuminate, occasionally piliferous; costa to 40-80% leaf length, moderate to somewhat stout, terminal spine present or absent; alar cells usually differentiated, larger or smaller than basal cells, ; laminal cells usually linear, <8-15:1, occasionally 20:1 or 3-5:1>, walls thin to moderately thick, rarely as thick as lumen (B. cirrosum and B. turgidum); basal cells shorter, often wider than more distal cells, . Branch leaves usually smaller and narrower; apex more gradually acute or acuminate. Sexual condition autoicous or dioicous; perichaetial leaves reflexed, apex gradually or abruptly acuminate. Seta red-brown with some variation in color in different species, darker with age, rough or smooth. Capsule inclined, horizontal, or somewhat pendent (erect in B. acuminatum), color similar to that of seta, usually darker, ovate, elongate, or cylindric, straight to curved; annulus not separating or separating by fragments; operculum conic, sometimes broadly short-rostrate; peristome xerocastique, perfect (reduced in B. acuminatum). Calyptra naked. Spores 9-25 µm.
SELECTED REFERENCE Ignatov, M. S., I. A. Milyutina, and V. K. Bobrova. 2008. Problematic groups of Brachythecium and Eurhynchiastrum (Brachytheciaceae, Bryophyta) and taxonomic solutions suggested by nrITS sequences. Arctoa 17: 113-138.