THE ECOLOGY OP PLANTS. 



453 



The other conspicuous plants of the pond-hollow are : (a) Water 

 Sweet-grass (Glyceria aquatica), occupying the centre except the parts 

 utilised by the Pondweed and Bur-reed ; (b) Iris pseudacorus at the 

 southern or inflow end ; (c) Marsh Horsetail (Equisetum palustre) at the 



Iri*. 



== Pondweed. 



Water Sweet-grass. 



Rushes. 



1 = 



Bur-reed. 

 Marsh Horsetail. 



Fig. 184. "Dry" Pond. 



northern or outflow end ; (d) a broad marginal zone of Rushes. The 

 large patch of Water-grass indicates the part of the hollow which is 

 occasionally under water. It is a feature of this grass that it grows 

 well in a moist place liable to inundation. The Iris and Marsh 

 Horsetail occupy well-defined areas, and both are typical marsh 



