Plants 1.2-10 × 1-2.5 mm. Stem unbranched and branched; axillary hyaline nodules present; central strand weak or absent. Leaves as many as 25 pairs, narrowly lanceolate to ovate-lanceolate, acute to sharply acute to short acuminate, to 1.9 × 0.3; dorsal lamina narrowed proximally, ending before or at insertion, infrequently ± decurrent; vaginant laminae 1/2-4/5 leaf length, ± equal, minor lamina ending on or near margin; margin entire, limbate on all laminae, limbidium confluent at apex or ending shortly before apex, extending to base of dorsal lamina, limbidial cells 2-3-stratose; costa percurrent to excurrent, bryoides-type; laminal cells 1-stratose, distinct, smooth, ± bulging, firm-walled, elongate, 7-22 × 4-13 µm, increasing in size toward proximal part of leaf. Sexual condition rhizoautoicous; perigonia gemmiform, proximal to infertile and fertile stems. Sporophytes 1 per perichaetium. Seta to 12 mm. Capsule theca exserted, ± erect, radially symmetric to inclined, arcuate, bilaterally symmetic, 0.35-1.25 mm; peristome bryoides-type; operculum 0.25-0.3 µm. Calyptra cucullate, smooth, 0.5 mm. Spores 11-18 µm.
Bare, shaded soil, often among grasses in open Quercus forests and around bases of coastal shrubs; Calif.; Mexico; West Indies; South America; Europe; Asia; Africa; Pacific Islands (New Caledonia, New Zealand); Australia.
Fissidens curvatus is distinguished by its delicate dimorphic stems, usually long excurrent costa, limbidium confluent at leaf apex, and slightly elongate laminal cells. The theca is usually arcuate but can also be erect.