J. Hattori Bot. Hypnum falcatum S. E. Bridel, Musc. Cratoneuron commutatum var. Stem sparsely pinnately or irregularly branched. Paraphyllia few or numerous.
Branch leaves smaller than stem leaves, differing only slightly in shape.
R. Ochyra records, belong to this species. When well developed, P. falcata differs from both P. commutata and P. decipiens in its larger size and the more sparse and often irregular branching pattern. In P. falcata the stem and branch leaves are similar in shape, whereas in P. commutata and P. decipiens they differ markedly. The alar cell group is mostly strongly expanded in its marginal part in P. commutata and P. decipiens , not so in P. falcata , and the areolation of the stem leaves is usually more regular in P. falcata than in the other two. However, because the original label information does not even indicate that the Salem where the specimen was collected is situated in North America, its true origin is doubtful.