Ch. XI] 



THE PEAT MOSSES 



485 



elaborate and highly specialized structure provided with 

 chlorenchyma. Some 12,000 species are known, but only 

 the Peat Mosses have any economic uses. The name is 

 wrongly extended in some cases to plants which are not 

 Mosses, as e.g. Sea Mosses, Long Moss, Spanish Moss, 

 Reindeer Moss, etc. They fall into two principal orders, 

 viz : 



Order 1. Sphagnales : the Peat Mosses. 

 Order 2. Bryales: the True Mosses. 



Order 1. Sphagnales: the Peat Mosses. These are 

 very soft-spongy Mosses occurring only where ground 

 water is plentiful ; and oftenest they 

 form close mats or tussocks in wet woods, 

 or else fill shallow ponds. They belong 

 all to one genus, Sphagnum, having 

 about 250 species, mostly in temperate 

 and arctic regions. Their very slender 

 stems (Fig. 344), part creeping and part 

 upright, grow indefinitely at the tips, 

 often branching, and thus may attain 

 great length and age (page 115). The 

 leaves, one cell layer thick, consist of 

 alternate rows of chlorenchyma and 

 larger, empty, perforated cells, which 

 absorb and hold water by capillarity 

 (Fig. 345) ; and as the stems are clothed 

 with similar cells there results a very 

 unusual power of holding water, which 

 is one of the chief characteristics of these 

 mosses. In exposed places they are 

 mostly red in color, but are bright green 

 in shade. The antheridia occur singly 

 in the axils of the leaves on special short 

 branches, while the archegonia termin.it e 

 the upper branches, where they are (From Kemer.) 



Fia. 344. — Sphag- 

 num cymbifolium ; X f 



