WATERSIDE WEEDS. 175 



the reed-mace. It grows by the edge of shallow waters 

 only ; and since these are very liable to dry up or shift 

 their place from time to time, it requires great numbers 

 of easily dispersed seeds, so as to take advantage of every 

 new habitat which petty topographical changes may 

 put at its disposal. Hence wind fertilization and winged 

 fruits exactly suit its special needs ; and in adaptation 

 to those needs it has become, perhaps, the most degraded 

 type of flowering plant now in existence, save only the 

 little floating stalkless duck-weed which forms a green 

 film on the surface of the half -stagnant water at its base. 



