The genus Sematophyllum is revised for the Iberian Peninsula, where it is represented by two species, Sematophyllum substrumulosum (Hampe) E. Britton and S. demissum (Wilson) Mitt. The gametophyte and sporophyte of both species are described from Iberian samples; the names of both species are lectotypified and their distributions are brought up to date by revising numerous herbarium specimens; phytosociological and habitat data are provided. The type of Hypnum bottini Breidl., a taxon known in the Iberian Peninsula from only one locality, is studied and compared with the original material for this citation. It is concluded that this is the taxon in question but that it should be considered as a species of Isopterygium (I. bottinii (Breidl.) Kindb.) (Hypnaceae).