20 HISTORY OF BRITISH MOSSES, 



to view tliem in contrast M'itli tliesCj in order to give be- 

 ginners some general idea of their form and structure. 



In the first place, then, the leaves of ]\Iosses are in every 

 case destitute of a footstalk — an appendage so frequently 

 met with among higher forms — but are attached to the stem 

 by the lower edge, sometimes also folding over and clasping 

 by the sides, thus rendering them imbricated, decurrent, etc. 

 Unhke those of other plants, they are always simple and 

 undivided, the only irregularity at the margins being more 

 or less distinct serratures, which are sometimes thickened, 

 and afford characters for distinction of species. The next 

 particular in which we may note a peculiarity, is the absence 

 of anything approaching to hairiness or pubescence on the 

 surface. To the inexperienced there are many seeming ex- 

 ceptions to this rule, as some TricJiostomums and Grimmias 

 seem more like downy cushions than anything else : on 

 closer examination, these hairs will be found to prove the 

 elongated bristle \vith which every little leaf is tipped ; the 

 rootlets springing from the stems and leaf-margins of 

 several species, are also appearances apt to mislead. The 

 fourth and last distinguishing mark worthy of notice, is the 

 persistent character of Moss-leaves, — that is, they do not 

 decay and fall off like the leaves of trees and other plants 



