60 MOSSES. 



beyond the point, rendering them bristle-pointed. 

 The seeds (fig. 49 a) are small and green. 



This moss serves to illustrate a great difficulty, 

 which will often occur to the student, in determining 

 whether a moss is end-fruited or side-fruited. For in 

 this, as in many other end-fruited mosses, a little 

 side-shoot or young branch (innovation) grows from 

 the main stem immediately below the leaves sur- 

 rounding the base of the fruit-stalk, so that the fruit- 

 stalk appears to arise from the side of the stem. The 

 only method of overcoming the difficulty is to ex- 

 amine carefully the comparative size and thickness of 

 the stem and the shoot, and to determine which is 

 the weaker and so the newer. The leaves surround- 

 ing the base of the fruit-stalk, which are mostly 

 somewhat different in structure from the stem- 

 leaves, are called the perichce tial (Tre/ot, around, %a/r?7, 

 bristle) leaves. 



From among the side-fruited or Pleurocarpous 

 mosses we shall select one only, Hypnum rutab'ulum 

 (PL III. fig. 43), which is common on the trunks of 

 trees and on banks. 



In this moss, the nodding unequal curved capsule 

 (fig. 45) has a double peristome, resembling that of 

 Bryum (fig. 47). The calyptra is half-cleft, and the 

 lid conical and shortly beaked. The stem is reclining 

 or procumbent, and the pale green imbricated leaves 

 (fig. 41) are ovate and pointed, faintly saw-edged, the 

 nerve becoming indistinct at about the middle. It 

 will be noticed that the cells of the leaf (fig. 48) 

 have the prosenchymatous form, or are elongate with 

 pointed ends ; and that the fruit-stalk (fig. 45) is 

 rough with little grains. 



Fructification. The fruit-producing organs of the 

 mosses are of two kinds, comparable to those of the 

 flowering plants, but with their names changed, as in 

 the case of the ferns; the representatives of the 

 anther being called antheridia, and those of the pistil 



