Cynodontium Bruch & W. P. Schimper, 1856.

Cynodontium is one of a number of plants in the Dicranaceae that may make the uninitiated think of the Pottiaceae. Species of this genus may have papillose cells, and those cells are often quadrate. With experience, however, the quadrate cells of the Dicranaceae are distinguishable from the isodiametric cells typical of the Pottiaceae. The shape of the lumen of an isodiametric cell of the Dicranaceae is angular, therefore almost square in dorsal view; the shape of the lumen of an isodiametric cell of the Pottiaceae is rounded, therefore almost circular. Our several species of Cynodontium can be quite confusing with only C. strumulosum showing all of the characters we associate with the genus: papillose cells, serrulate to crenulate and bistratose leaf margins, and strumose capsules. One should consider this genus for small plants with crispate leaves and nearly isodiametric cells but without sheathing leaf bases. The only California species, Cynodontium jenneri, occupies rock outcrops at high montane elevations.
see Keys to Dicranella, Dichodontium Etc.

Species included:
Cynodontium jenneri (W. P. Schimper in Howie) Stirton
Cynodontium strumulosum C. Müller Hal. & Kindberg in Macoun, not known from CA
Cynodontium tenellum (Bruch & W. P. Schimper) Limpricht, excluded by Malcolm et al. 2009

A. Median leaf cells papillose or papillose on high mammillae; leaf margins unistratose .....Cynodontium strumulosum not known from CA
A. Median leaf cells smooth or mammillose .....B

B. Leaf margins unistratose; perigonium with acute bracts; median leaf cells mostly more than 12 µm wide .....Cynodontium jenneri
B. Leaf margins bistratose; perigonium with obtuse bracts; median leaf cells mostly less than 10 µm wide .....Cynodontium tenellum