Verh. K. K. Zool.-Bot. Ges. Wien 19: 503. 1869 ,.
Plants gregarious to tufted, mostly small and soft. Stems erect. Leaves with margins plane to recurved, mostly crenulate distally, sometimes entire, apex rounded; costa short to elongate, ending at midleaf to percurrent or shortly excurrent; distal cells of leaf in ascending rows diverging from costa. Sexual condition antheridia ripening asynchronously within each perigonium, surrounded by a few short broad bracts, or the bracts not much differentiated from vegetative leaves; perichaetial leaves not differentiated. Capsule short-cylindric to obpyriform, with scanty phaneropore stomata at base; peristome set deep inside capsule mouth, the teeth wide-spreading when dry, connivent over the mouth of the capsule when moist. Calyptra scarcely cucullate.
R. S. Breen and R. A. Pursell (1959), after reviewing specimens of Splachnobryum from the United States, Mexico, Central America, and the West Indies, recognized only S. obtusum. They placed many names into the synonymy of S. obtusum, although apparently without examining the types of all the names they synonymized. The species of Splachnobryum commonly grow on basic substrates in moist situations; they are sometimes tufa-forming mosses. Although archegonia are often present in specimens, antheridia and sporophytes are uncommon. Identification to the species level usually must be made with sterile specimens, which generally lack well-defined taxonomic characters. As a consequence, much herbarium material must be considered to be only tentatively identified to species. This especially applies to the populations in the flora area, which is marginal to the main world range of the genus and where the plants are always sterile. In part due to the absence of reliable and repeatable means to sort specimens from the flora area, they are here all assigned to a single species, S. obtusum.