Distribution
Region: nearly worldwide, tropical and subtropical regions.
Genera: ± 16; ± 200 species.
BotanyMoss; medium-sized to large.
Stems: often with basal stipe region, foliose, simple or pinnate, branches flagelliform; cortical cells orangebrown, walls thick, central strand not differentiated; paraphyllia absent; pseudoparaphyllia filamentous, 1-seriate, hyaline; stolons creeping, becoming erect, inclined, or horizontal, rhizoids usually restricted to stolons.
Leaves: stolon leaves scalelike, 0.2–1.3 mm; apex short-acute or long-acuminate; usually ecostate; stipe leaves appressed, erect, or recurved, triangular to ovate-acuminate; base clasping; costa double or single, shorter in distal stem-leaves; stem-leaves appressed, erect, spreading, recurved, or squarrose, ovate-acuminate, ovate-orbicular, oblong-lanceolate, oblong-ovate, or ovatelanceolate, concave; margins plane or rarely revolute to apex, entire, or serrulate distally; costa single or double and short; alar cells little differentiated, or rhombic to quadrate in several rows along margin, or rarely region well differentiated, large, conspicuous; proximal laminal cells at insertion dark yellow, walls porose, thick, irregular; medial cells sinuate or linear-flexuose, smooth, prorate, or rarely 1-papillose, walls often porose; distal cells shorter; branch leaves similar to or differentiated from stem-leaves, narrowly ovate-acuminate, concave, not or weakly plicate, sometimes smaller.
Sexual reproduction: asexual frequent, by clavate gemmae in clusters in leaf-axils, reddish-brown, 1-seriate, of 4–12 quadrate or rectangular cells, walls thick, verrucose; sexual condition dioicous; perigonia on stem and branches, budlike, leaves few, scalelike, paraphyses 1-seriate, antheridia 5–10; perichaetia on stem and branches, urceolate, leaves 8–12, interior ones ovate-acuminate, abruptly narrowed to long, erect awns, paraphyses often present, multiseriate.
Capsule: erect, exserted, redbrown, narrowed to mouth, smooth; stomata absent; annulus usually absent; operculum short, rounded or conic, rostrate; prostome present; exostome reduced, teeth 16, often in 8 irregular pairs, incurved when dry, erect when moist, lanceolate, often irregular, inserted below mouth, mostly smooth; endostome of remnants adhering to back of exostome, cilia usually absent; seta redbrown, elongate; calyptra cucullate, fully or partly covering capsule, with scattered archegonia and paraphyses or smooth, not plicate. Spores spheric or ovoid, 20–35 µm, granulose, green.
Genera: Calyptothecium, Cryptogonium, Henicodium, Hildebrandtiella, Horikawaea, Jaegerina, Micralsopsis, Muellerobryum, Neolindbergia, Orthorrhynchidium, Orthostichidium, Orthostichopsis, Osterwaldiella, Penzigiella, Pireella, Pseudopterobryum, Pterobryidium, Pterobryon, Pterobryopsis, Renauldia, Rhabdodontium, Spiridentopsis, Symphysodon, Symphysodontella.