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CHAPTER XXIII 



THE ECOLOGY OF WATER PLANTS 



THE study of the relation of plants to their habitats, 

 of their different forms of association with one another, 

 and of their appHed physiology in general, is at the present 

 day commonly included under the name of ' Ecology,' around 

 which a complicated system of other technical terms has grown 

 up. But, though the ecological language is new, the ecological 

 standpoint and even the special ecology of water plants, are as 

 old as the science itself. Theophrastus (370 B.C.-285 b-c.)> 

 whose writings form our earliest botanical classic, distinguishes 

 water and marsh plants as a biological group and classifies them 

 according to their varieties of habitat^. 



In a country such as Great Britain, where cultivation of the 

 land, grazing of flocks and herds, and the numberless activities 

 of man, have reduced the terrestrial plant population to a mere 

 disheartening semblance of its former self, the vegetation of the 

 waters has preserved, in many cases, a closer approximation to 

 its original condition. Despite periodical disastrous clearances, 

 ponds and streams, even in highly cultivated regions, some- 

 times show a fairly natural grouping of their inhabitants, while, 

 on dry land, such a grouping can often only be discovered in 

 remote districts, such as our few remaining areas of virgin fen 

 and forest. 



At the present day a voluminous literature has come into 

 existence dealing with ecological topics, but it must be confessed 

 that, as regards water plants, the results attained are, on the 

 whole, scarcely of first-rate importance. On analysing the work 

 in question, one is led to the conclusion that the chief service, 

 which Ecology has rendered to the study of water plants, has 

 probably been in emphasizing the influence of the substratum 



^ Greene, E. L. (1909). 



