216 



BOTANY. 



they form dense moist cushions, often of great extent. 

 On account of peculiarities in the structure of their leaves 

 they are enabled to absorb and hold large quantities of 

 water, and for this reason they are extensively used for 

 "packing "in the transportation of living plants. They 

 all belong to the genus Sphagnum. (3) Order 36, Ak- 

 CHiDiACB^, small mosses with but little development of a 

 leafy stem, and a persistent protonema. 



400. (4) The True Mosses (Order 27, Beyace^) in- 

 clude the great majority of the species of this class. 

 They are usually bright green (in a few genera brownish). 



Fto. 127.—^, three spores of a Moss germinating ; B, protonema of a 

 Moss ; K, a bud from which a leafy stem will develop. Highly magnified 



and in most instances live upon moist ground and rocks, or 

 upon the bark of trees ; in a comparatively small number 

 of cases the species live in the water. They are undoubt- 

 edly the highest of the class, and show a greater differen- 

 tiation of tissues than any of the preceding orders. Among 

 the more common mosses are species of Dicranum, Fissi- 



