HOLE : SOME. INDIAN GRASSES AND THEIR CECOLOGY. 11 



9. Warming further recognises an associa- The Associft - 

 tion as " a community of definite floristic composition within a formation; it is, so to speak, 



a floristic species of a formation which is an ecological genus." A forest, for instance, 

 obviously diners according to its constituent species and this author thus recognises deci- 

 duous dicotylous forest in the temperate climate as a mesophilous formation of which 

 Beech Forest, Oak Forest, and so on, may be considered different associations. He also 

 notes that, as different beech forests are not always identical in character, we may recog- 

 nise varieties of an association. 



10. The classification adopted by ISchimper scwmper's 



\ " Classiflca- 



differs in some respects from that detailed above. Inis author also distinguishes Aquatic tion. 

 Plants (Hydrophytes) from Terrestrial Plants but then proceeds to classify the latter as Tropophytes.' 

 follows : — ■ 



" Contrivances for expediting the exit of water are characteristic of hygrophytes, or 

 plants whose conditions of life exclude all danger of desiccation, and in which a stagnation 

 of the water, which brings nutritive salts to the parts requiring them, may be feared. On 

 the other hand, difficulties in obtaining a supply of water lead to the formation of devices 

 for assisting absorption and limiting transpiration; xeropliytes are provided with contri- 

 vances of this kind. 2 



He also places in a third category — 



" all plants whose conditions of life are, according to the season of the year, alter- 

 nately those of hygrophytes or of xeropliytes. All such plants, including, for 

 instance, the great majority of the plants composing the Central European 

 flora, should be termed tropophytes. The structure of their perennial parts 

 is xerophilous, and that of their parts that are present only in the wet season 

 is hygrophilous."" 

 He then distinguishes — 



Rain- forest ( = Evergreen forest) as a hygrophilous formation of tropical woodland 

 and 

 Monsoon-forest ( = Deciduous forest) as a tropophilous formation of the same. 

 Schimper's hygrophytes and tropophytes as a whole are included in Warming's mesophytes. 

 The Indian Forester will appreciate the wide separation of the tropical evergreen from the 

 deciduous forests of Schimper's scheme. 



11. Warming endeavours to carry classifica- Warming's 

 tion a step further by grouping all formations under a series of classes of which the follow- of Forma- 1 



n tions. 



mg are examples : — 



Psammophytes (formations on sand and gravel), 

 Eremophytes (formations on desert and steppe), 

 Halophytes (formations on saline soil). 



1 I.e., p. 145. 



2 I.e., p. 2. 



3 I.e., p. 3. 



C ii } 



