1 8 HOW TO KNOW THE MOSSES 



The arrangement and position of the leaves are 

 important characteristics in determining mosses, and 

 ones that can be easily studied. 



Leaves usually grow all around the stems and 

 branches (Plate III, Fig. 9), but in Fissidens (p. 97), 

 Distichium (p. 83), and in a few other genera not in- 

 cluded in this book, they are arranged in only two 

 rows on opposite sides of the stem and He flat like the 

 pinnae of a fern (Plate III, Fig. 10). They are called 

 ''erect" when they He about parallel with the stem 

 (Plate III, Fig. 11); "wide-spreading," when they 

 stand out nearly at right angles to the stem (Plate III, 

 Fig. 12) ; '' erect-spreading," or '' not wide-spreading," 

 when they are between erect and wide-spreading; and 

 ''turned to one side" (secund), when they look as if 

 blown in one direction (Plate III, Fig. 13). In some of 

 the pleurocarpous mosses the leaves appear in two 

 rows when they are evenly parted and turned in two 

 opposite directions (Plate III, Fig. 14). 



There is often a difference in the position of the 

 leaves when moist and when dry. For instance, leaves 

 that are wide-spreading when moist may become 

 closely folded when dry instead of becoming crisped; 

 in other cases they are not much changed in drying. 



Many shades of green are found in the mosses. Some 

 are glaucous (whitish) or bluish, some golden or yel- 

 lowish, and some bright, olive, or dark green. There is 

 often a variation in color, even on the same plant, as 

 the oldest leaves turn brown or dark, while the young- 



