In recent treatments of Fissidens subgenus Fissidens Hedw., the species delimitation of Fissidens bryoides Hedw., the type species
of the subgenus, has been rather variable. Depending on the value given for
different morphological characters, F.
bryoides in Finland has been splitted either into three species, F. bryoides, F. gymnandrus Buse  and F. viridulus (Sw.) Wahlenb., or
treated as a single species, F.
bryoides s. lat., including two or more intraspecific taxa. The herbarium
material of Finnish Fissidens bryoides,
F. gymnandrus and F. viridulus was studied to clarify the distribution
and ecological requirements of the three taxa and to test which morphological
and ecological characters serve in their delimitation. The phylogeny lends
support for a taxonomical treatment distinguishing Fissidens bryoides s. lat. including F. gymnandrus and F.
viridulus at the infrageneric level as F.
bryoides var. gymnandrus (Buse)
R. Ruthe and F. bryoides var. viridulus (Sw.) Broth.