Sematophyllum Mitten, 1864.

Our only species of this largely tropical genus has been reported from Eucalyptus plantings in the city of San Francisco, and we believe it to be introduced. The genus Sematophyllum is a prostrate pleurocarpous and ecostate moss. The distinguishing character is the single row of 3-5 greatly enlarged and thin-walled cells at the alar angles.
see key to Hypnum Etc.

Species included:
Sematophyllum adnatum (Michaux) E. Britton