SPHAGNUM MOSS NICHOLS. 225 



when dry, it may be almost white. Very frequently the green is 

 hidden almost completely by pigments of various colors, so that the 

 plants may be almost any shade from bright red and pink to russet 

 green and dark brown or almost black. These colors form a very dis- 

 tinctive feature of many sphagnums when they are fresh; in nature, 

 their mass effect is very striking, and they are of great help when 

 it comes to recognizing material in the field. 



But color alone is hardly a sufficient test. Other distinguishing 

 marks are afforded by the peculiarities of the branches and of the 

 leaves. If a single sphagnum plant is examined it will be seen, first 

 of all, that it consists of a main axis, on which are borne numerous 

 short branches. It will be noted, further, that these branches are riot 

 borne singly, but in clusters of from three to six. No other moss pro- 

 duces its branches in clusters, after the manner of the sphagnum. 

 Along most of the stem these branch clusters are scattered, but toward 

 the tip they usually grow so close together as to form a rather 

 compact rosette which sometimes is mistaken for a flower. It might 

 be added that the branches in each cluster are of two sorts: One 

 kind stands out at right angles to the main axis; the other kind 

 droops down alongside the stem and forms a sort of loose, spongy 

 matting around it. 



And not only is the arrangement of the branches on the 

 stem distinctive. Quite as striking is the arrangement of the 

 leaves on the branches. Every branch is completely covered 

 over by a series of tiny, more or less spoon-shaped leaves, which 

 loosely overlap one another, somewhat after the manner of tiles 

 on the roof of a house. 



STRUCTURAL PECULIARITIES TO WHICH SPHAGNUM OWES ITS EFFICIENCY 



AS AN ABSORBENT. 



To a limited degree certain of the features already described 

 adapt the sphagnum to absorb liquids — the overlapping of the 

 leaves around the branches, and the sponge-like matting of the 

 pendent branches around the stem. But the real secret of the 

 sphagnum's efficiency as an absorbent lies in the remarkable micro- 

 scopic structure of its leaves. 



Before discussing the somewhat complicated sphagnum leaf, I will 

 describe briefly the much simpler structure of an ordinary moss leaf 

 as it looks under the microscope (fig. 1). Such a leaf consists of a 

 single layer of tiny microscopic cells. Seen in surface view the in- 

 dividual cells are polygonal in outline, but in reality, considered as 

 solids, they are prismatic in shape. All the cells in the leaf are 

 essentially similar to one another; without exception they are green 

 and living, and they are all of approximately the same size and shape. 



