A MOSS 87 



where otherwise only a few much simpler plants can live ; on 

 the faces of rocks, where food material is scanty ; on decay- 

 ing wood, and the trunks of living trees ; on the soil of deeply- 

 shaded forests ; in shallow water, and in bogs and marshes. 

 Some mosses, like the one we are to study, can endure long 

 dry spells and can resume growth upon the return of moisture. 

 Not all mosses are adapted to all of these different condi- 

 tions ; but each sort of location has its characteristic species. 



One of the commonest mosses is Funaria hygrometrica 

 (Fig. 43, A), which is selected for the present study. It 

 grows on dry or well-drained soil, on roadsides, in open 

 fields, gardens, and waste places. When it is fruiting it may 

 be recognized by its very numerous, reddish, curved, pear- 

 shaped spore sacs, which are borne on slender, twisted, red 

 stalks. 



115. The Moss Plant. What is commonly thought of as 

 a moss plant has an upright stem which bears green leaves and 

 colorless or brownish, hair-like rhizoids. A great difference 

 between the moss and any of the fungi or algas is in the fact 

 that its body is divided into stem and leaves. This upright 

 plant is especially well adapted to secure light, carbon dioxid, 

 and oxygen. The stem, supports the leaves in a position 

 favorable for their work, and conducts food substances from 

 place to place within the plant. For these purposes, the stem 

 has become a compact, cylindrical structure. It is more or 

 less green because its outer cells contain some chlorophyl, 

 but for the most part the manufacture of carbohydrates is 

 carried on in the leaves, and only a small part of this work 

 is done in the stem. Besides leaves and rhizoids, the stem 

 bears, usually near its base, occasional branches. A leaf 

 (Fig. 43, B) is the part of the plant that is chiefly concerned 

 with the manufacture of food substances, particularly of 

 carbohydrates. It has a midrib, made up of long, slender 

 cells. The rest of the leaf, to right and left of the midrib, is 

 composed of a single layer of green cells. 



