26o PLANT LIFE. 



runners rooting at the tip, as well as long horizontal 

 roots which traverse the moss turf in every direction. 

 It has also fleshy leaves, so that it can resist dry 

 weather, during which on account of its situation no 

 moisture reaches it. 



Generally, however, other mosses of the second 

 group, with a prostrate creeping habit, cover over 

 these tufts of Didymodon, Bryum, Dicranella, or others. 

 Except for their habit of growing on walls and forming 

 dense turf underneath, they differ in every respect from 

 the upright forms. Generally, they produce circular or 

 oval patches, because the branches grow out from a 

 common centre. These branches give off numerous 

 branchlets, which are arranged in a pinnate or feathery 

 manner ; and, from the under side of all the branches 

 and their divisions, little bunches of brown absorbing 

 rhizines are given off, which fix themselves on the 

 dying mosses below, and absorb whatever they can. 

 When a particular branch has grown a certain distance 

 from the common centre, the older part of it begins to 

 grow brown and decay ; then it is attacked by younger 

 branches, which, beginning near the centre, curve over 

 the older ones, and eventually extend beyond them on to 

 a fresh part of the wall. These younger branches are 

 in no way particular, and attach their absorbing rhizines 

 to the parent branches below, or to any other likely 

 material which they can reach. In fact, in most cases, 

 it looks as if these branches were directly parasitic upon 

 the older ones. These branching plumose feathery 

 mosses, belonging to the old genus Hypnum, now sub- 

 divided into numerous sub-genera Brachytliecium, Plagio- 

 thecium, Eurhyncliium, etc., generally occur in woods, 

 and especially in wooded lynns or ravines, where they 

 are important constituents of the " wood floor." They 



