138 HOW TO KNOW THE MOSSES 



The distinguishing characteristic of the Mniums is 

 the broad, flat leaf of a thin, gauzy texture, which en- 

 ables the student quickly to learn to recognize the 

 genus. The rosettes resemble Rhodobryum, the pre- 

 ceding genus, but the leaves grow on the lower part 

 of the stem as well as at the tip. Sometimes the 

 leaves appear to be on opposite sides of the stem, as 

 in Fissidens (p. 97), but the leaves are larger, more 

 separated, and a careful examination will show that 

 they are arranged in more than two rows. Aulacom- 

 nium heterostichum (p. 140) somewhat resembles certain 

 Mniums; for comparison see under that species. Care 

 must be taken not to mistake the round leaves of 

 certain hepatics for those of Mnium. The conspic- 

 uous leaves of the hepatics are arranged in only two 

 rows, are somewhat thicker, usually smaller than in 

 most of the Mniums, and are not so fiat, as they often 

 curl under at the tip. (See Introduction, p. 6.) 



