Land-building Plank 



303 



in taking a good hold on the bottom, then other shoots 

 spring from this new center and repeat the process 



d is the method of the cat-tail flag. It consist in 

 developing an abundance of interlaced fibrous roots 

 and then simply floating on them. Much mutual sup' 

 port is required by ^plants that grow so tall; and any 

 great advance of a few clumps beyond the general front 

 may result in disaster from overturn by winds 



eis a method of mutual support between sjiecies of 

 very different sorts. It is that of the sphagnum and 

 heaths just discussed. Greater progress over deeo 

 water is made by this method than bv any of the oth< srs 



A photograph of the first named is "reproduced as 

 figure 212. 



Fig. 212. A bit 



of running 

 root-stock of 

 a spike rush. 

 Eleo charts 

 p a I u s tris, 

 showing its 

 method of ad- 

 vance over the 

 pond bottom. 

 Bra nching 

 subterranean 

 off-shoots ex- 

 tend down a 

 sloping shore 

 until t h e y 

 reach a depth 

 of water in 

 which they 

 cannot func- 

 tion effec- 

 tively. 



