Land-building Plants 



355 



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 consists 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. 



e is a method of mutual support between species of 

 very different sorts. It is that of the sphagnum and 

 heaths just discussed. Greater progress over deep 

 water is made by this method than by any of the others. 



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 lu stris, 

 showing its 

 method of ad- 

 vance over the 

 pond bottom. 

 Bra nching 

 subterran e a n 

 off-shoots ex- 

 tend down a 

 sloping shore 

 until they 

 reach a depth 

 of water in 

 which they 

 cannot func- 

 tion effec- 

 tively. 



