Serrate Aphanorrhegma Moss

Aphanorrhegma serratum resembles the sympatric Physcomitrella patens, from which it differs in its capsule’s regular line of dehiscence and collenchymatous exothecial cells; it also grows occasionally with Physcomitrium immersum. The latter two species are small and both have an immersed operculate capsule. Physcomitrium immersum is distinguished by a distal line of dehiscence (versus equatorial in A. serratum), the presence of an annulus of small cells, the thin-walled (versus collenchymatous) exothecial cells, and an urceolate rather than a globose operculate urn. Aphanorrhegma serratum has been reported from Texas by H. A. Crum and L. E. Anderson (1981). I have seen only one collection (Duke) from that state, but the specimen lacks collenchymatous exothecial cells, bears a distinct annulus, and hence is here referred to Physcomitrium immersum.

Plants gregarious to scattered; leaves slightly twisted when dry; perichaetial leaves erect-spreading when dry, exposing the capsule.

Schistidium serratum Wilson & Hooker, Musc. Amer. S. States 2: no. 20. 1841

Aphanorrhegma is a genus of moss in the family Funariaceae. It contains the single species Aphanorrhegma serratum distributed in eastern North America.