VASCULAR FLOWEELESS PLANTS. 77 



of the vascular and fibrous tissues of the stem take an 

 ascending direction, and associated with the horizontal cellular 

 tissues forms the branches and leaves ; the other part take a 

 descending direction, and contribute to the formation of the 

 roots and fibres in the soil. 



101. It is true that in the mosses we have the higher type 

 of vegetation fully realized. We have an ascending axis or 

 stem clothed with symmetrically arranged leaves, and a 

 descending axis or root, in these humble plants, although 

 their structure is wholly cellular. It is not surprising, how- 

 ever, that in this instance the cellular system should take a 

 vertical development, since we have shown that the vascular 

 and fibrous vertical system is only a modification of the cell- 

 ular. The cells of the sphagnums or bog-mosses contain 

 spiral fibre, and woody fibre seems to be faintly foreshadowed 

 in those elongated cells which form the nerves of the leaves 

 of many mosses. Mosses, owing to their cellular structure, 

 seldom rise more than a few inches above the ground. Not 

 so with the 



LYCOPODIAOE^, OB, CLUB-MOSSES. 



102. In these plants we have a most decided advance in 

 organic development. In their general appearance, they 

 resemble mosses to which they are closely allied, although 

 they are much larger ; for, owing to the strength imparted by 

 the bundles of woody fibre running lengthwise through their 

 stem, they are enabled to rise to a greater elevation above the 

 ground, some of them growing two or three feet high. 



