Plants very small, yellowish green or brownish green, gregarious or in loose tufts. Stems erect, usually simple. Leaves long-subulate from a narrowed base; margins entire; costa thick, long-excurrent, often filling most of the subula; upper cells subquadrate, smooth; basal cells longer; alar cells not differentiated. Autoicous. Setae elongate, yellowish, straight or somewhat cygneous above; capsules exserted, erect, symmetric, oblong-cylindric, striate; opercula rostrate; annuli large, compound, in 2–3 rows; stomata present, small; peristome (endostomal segments) 16, very short, not or slightly exceeding the annuli, hyaline, papillose. Calyptrae narrowly conic-mitrate, divided at the base into 3–5 spreading lobes, smooth or obscurely plicate above. Spores spherical.

The genus Brachydontium consists of five rare species. Four of them have a narrow distribution with B. curvisetum Crum endemic to Mexico, B. flexisetum (Hampe) Par. restricted to Colombia, B. intermedium I. G. Stone only known from Australia, and B. olsonii Bowers & Allen confined to Honduras. Only B. trichodes (Web.) Milde is found to be more widely distributed in the Northern Hemisphere.

Lower Taxon

• Brachydontium trichodes (Web.) Milde