Isopterygium Mitten, 1869.

This is a species infrequently encountered in California, but that scarcity may result primarily from its frequent pattern of depauperate growth among other mosses. It is our only complanate and ecostate moss with conspicuous clusters of filamentous pseudoparaphyllia, especially along main stems. It should be looked for in rock crevices in montane areas.
see key to Plagiothecium Etc.

Species included:
Isopterygium tenerum (Swartz) Mitten