[3][4] The Global Biodiversity Information Facility considers it valid in its own right.
[5] The order includes plants that generally grow from a creeping primary stem with reduced leaves, and plants that have spreading to ascending secondary stems which may be pinnately branched.
Paraphyllia (tiny branched or stipuliform organs between the leaves) and pseudoparaphyllia are sometimes present on the stems.
The cells may be short or elongate and smooth or papillose, with those at basal angles sometimes differentiated.
The double peristome, sometimes reduced, consists of 16 teeth which are papillose on the outer surface, or less often cross-striate at the base, and an endostome with narrow segments and a low basal membrane or none at all.