Plants pale to dark green, sometimes becoming brownish to blackish, particularly in older parts, scattered to forming dense mats. Stems monomorphic or dimorphic, erect, usually becoming decumbent, unbranched and branched; axillary hyaline nodules present or absent, when present composed of 1-3 enlarged, bulging, hyaline cells arranged linearly (larger, multicellular, protruding); epidermal and subepidermal cells small, incrassate, pigmented or not, or enlarged, thin-walled, hyaline; cortical cells larger, thin-walled, hyaline; central strand present or absent; rhizoids tan to reddish, basal and axillary, usually smooth, infrequently papillose; axillary hairs 1-seriate, filiform. Leaves in few to numerous pairs, pinnately or palmately arranged, changing little to strongly crispate when dry, ovate to linear-lanceolate; vaginant laminae mostly acute, equal, ending on or near margin, or unequal, minor lamina ending between costa and margin, or, particularly in perichaetial leaves, rounded and free distally or narrowed and ending on or near costa; margin entire to serrate, marginal cells often differentiated into a limbidium; costa usually distinct, infrequently obscured, variable in length, absent or nearly so to short-excurrent, variable in structure (bryoides-type, oblongifolius-type, taxifolius-type; laminal cells usually eguttulate, rarely guttulate, 1-stratose, or 2-stratose in patches, rarely 3- or more stratose, smooth, plane, bulging, mammillose, 1-papillose, or pluripapillose, small, firm-walled, rounded to irregularly hexagonal, changing little when dry, to large, thin-walled, hexagonal to oblong cells, usually shrunken when dry [rarely prosenchymatous]. Specialized asexual reproduction uncommon [by globose, multicellular, subterranean gemmae (tubers) or axillary, stalked, multicellular, clavate or filiform gemmae], rarely by chlorophyllose, branched filaments at bases of leaves. Sexual condition dioicous, autoicous, or rarely synoicous. Perigonia gemmiform, axillary, or at bases of stems, or sometimes scattered among persistent protonemata on substratum, or terminal on longer stems. Perichaetia terminal on main stems and long branches, or terminal on short axillary branches. Seta 1-2 [rarely more], smooth [papillose], straight or flexuous, yellow when young, darkening with age, or reddish. Capsule usually exserted, theca erect or infrequently ± inclined, infrequently arcuate, radially or bilaterally symmetric, ovoid to cylindric, smooth, usually stomatose, rarely estomatose, stomata few, in proximal part of theca, phaneroporous; exothecial cells quadrate to oblong, longitudinal walls often thicker than cross walls, frequently collenchymatous; annulus none, abscission zone present; peristome variable; operculum conic, short- to long-rostrate. Calyptra mostly cucullate, infrequently mitrate, smooth or prorate. Spores smooth to finely papillose.
Species ca. 450 (37 in the flora): worldwide, mainly tropical areas.