HOLE : SOME INDIAN GRASSES AND THEIR CECOLOGY. 5 



and hence the factors which influence the healthy development and reproduction of such 

 insects and birds may determine the area within which a particular plant is able to exist. 



Finally the absence of a plant in localities suitable for its development may be 

 accounted for by the simple fact that its seeds have not yet been able to reach those localities. 



The importance of the direct injury inflicted by parasitic plants, such as fungi, by 

 injurious insects, or by browsing animals such as goats, in rendering the existence of a 

 particular plant in a certain locality impossible, is more obvious and needs no emphasizing 

 and these remarks will make it clear that the complete cecological study of a particular 

 species really comprises a complete knowledge of its physiology and pathology. 



6. The fact that, to a certain extent, a know- importance 

 ledge of the physiology of a plant can be obtained by a study of its morphology and anatomy logical and 

 is of great importance in ©ecology. Thus the morphological characters of the fruit may characters 

 indicate the agency by which the seeds are distributed, such as wind, water, animals, and in (Lco ° ey ' 

 so on; similarly the characters of the flower may indicate the agency by which pollination 



is effected, such as wind or insects, while' the morphological and anatomical characters of 

 the leaf and the habit of the plant may indicate whether it is adapted to exist in a sunny 

 or shady, dry or wet locality. 



By continually tracing the connection existing in different localities between such 

 characters of the vegetation and the factors of the environment, a mere inspection of the 

 vegetation existing in localities, not hitherto visited, eventually suffices to give a fairly 

 accurate idea of the chief factors influencing plant growth which exist there and thus 

 enables us to decide whether or not a certain species will be likely to thrive there. The 

 accuracy of such conclusions is greatly increased by a study of so-called indicator -plants. 

 If a species A, for instance, is invariably found on soil which is known to be suitable for 

 the vigorous development of species B, it is clear that we may regard the existence of A as 

 a direct indication of a locality suitable for B, at all events so far as the characters of the 

 soil are concerned. 



Grasses are particularly valuable in this respect and a careful study of the grasses 

 in forest blanks, in many cases, indicates to the Forester whether or not the conditions of 

 soil and moisture are such as to render possible the afforestation of such blanks with a 

 particular species, and similarly the existence of other grasses may indicate that the soil 

 has become unsuitable for a certain species and may thus explain why reproduction can no 

 longer be obtained in those forests. 



7. As the morphological and anatomical Existing 



r ° Schemes of 



characters of the vegetative organs, as well as the habit of plants generally, show the most Ecological 

 noticeable and striking variations in response to differences in the quantity of moisture tion. 

 available for growth, oecologists up to date have, as a rule, concentrated their attention 

 primarily on this factor and have made it the basis of their cecological classifications. 



Thus Professor Warming notes : ' Water is the condition of life that exercises the 

 greatest influence in bringing into being external and internal differences among plants; 



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