CHAPTER XXXI. 

 MOSSES (MUSCINE^E). 



483. General characters. The mosses are small, leafy- 

 stemmed plants usually growing in dense tufts or mats on the 

 ground, in swamps, moist woods, or in dry places, on rocks, 

 or on tree trunks, etc. Some of those on rocks and in dry 

 places can resist long periods of drought, becoming very dry, 

 and revive with the advent of rains. A few grow in the water. 

 Those not found in the water are nearly all erect, with three 

 distinct rows of leaves, and they are thus easily distinguished 

 from the foliose liverworts (see paragraph 478). The leaves 

 consist of a single layer of cells, except for a more or less 

 well developed midrib, which in some species only extends 

 a short way in the base of the leaf; in other species it is 

 longer and in some extends entirely through the leaf. This 

 midrib consists of narrow cells several layers in thickness. 

 Since the leaf is mostly one cell layer in thickness, the 

 starch grains in connection with the chlorophyll body are 

 easily seen with the aid of the microscope. The spores from 

 the capsule germinate and produce a branched filamentous 

 growth, the protonema, from which the leafy stem arises as a 

 branch. The general characters should be studied in one or 

 more examples followed by a study of the life history. The 

 "fruit" of the moss is a stalked capsule (sporogonium) ; rarely 

 is it sessile. The stalk is inserted in the end of the moss stem 



To THE TEACHER. One moss (Mnium, Polytrichum or Funaria) should 

 be studied in practical work. A very interesting collection of mosses can 

 easily be made and preserved dry on cards to illustrate the different habits 

 of the mosses. In field trips made during the year members of the class 

 will find it interesting to assist the teacher in making such a permanent 

 collection for the school. 



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