The spores of six species, namelyGrimmia decipiens, G. elatior, G. funalis, G. orbicularis, G. pulvinataandG. trichophyllawere studied by means of TEM, SEM and LM. TEM is here used for the first time on spores of this genus. Ultrastructural spore features allowed a clear characterisation of all six species. In addition, we observed the ultrastructure of the spore wall to be different from the typical Bryopsida type, with a multilaminar structure of the exine, not previously reported in mosses. The possible evolutionary, ecological and taxonomical significance of the spore features are discussed.