CHAPTER VI 



THE MOSSES (MUSCI) : SPHAGNACE^ ANDRE^ACE^ 



The Mosses offer a marked contrast to the Hepaticai, for while 

 the latter are pre-eminently a generalised group, the Mosses 

 with a very few exceptions are one of the most sharply-defined 

 and specialised groups of plants known to us. Although much 

 outnumbering the Liverworts in number of species, as well as 

 individuals, the differences in structure between the most extreme 

 forms are far less than obtain among the Liverworts, While 

 the latter occur as a rule in limited numbers, and for the most 

 part where there is abundant moisture, the Mosses often cover 

 very large tracts almost to the exclusion of other vegetation, 

 especially in northern countries. In more temperate regions, 

 the familiar peat-bogs are the best known examples of this 

 gregarious habit. Mosses are for the most part terrestrial, 

 and are found in almost all localities. Some grow upon organic 

 substrata, especially decaying wood, and are to a greater or less 

 extent saprophytic. Haberlandt ^ first called attention to this, 

 and investigated a number of forms, among them RJiynchostegiuin 

 murale, Euryndiimn prcslongum, Webera nutans, and others, and 

 in these found that the rhizoids had the power of penetrating 

 the tissue of the substratum, much as a fungus would do. The 

 most remarkable case, however, is Buxbaumia, where the leaves 

 are almost completely absent and the saprophytic habit very 

 strongly pronounced. Most of the Mosses, however, are 

 abundantly provided with assimilative tissue, and grow upon 

 almost every substratum, although most of them are pretty 

 constant in their habitat. A number of species are typically 

 aquatic, i.e. Fontinalis and many species of Sphagnum and 



1 Haberlandt (4). 



