,V2 



JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



from east to west, the two arms of the V roughly following the course of 

 the Indus and Ganges valleys. At the extremity of the easternmost arm 

 is found the luxuriant Ganges-area type, passing, on the west, successively 

 into the types of Jhind and the Punjaub to reach at the other (western- 

 most) limit the stunted Sukkur type, the character of which may be justly 

 described as of a distinct xerophytic nature. 



From an economic standpoint it was sufficient simply to note the 

 variations described ; it seemed, however, desirable to go further, and 

 establish, if possible, some explanation which would satisfactorily account 

 for the observed facts. Since the variations were of such a nature as to 



Fig. 9. — Mozuffergakh Plant. 



suggest the agency of climatic conditions, a study of these for Northern 

 India was undertaken. 



The two most important of the meteorological conditions which have 

 to be considered are the rainfall and the temperature. Map I. gives the 

 lines of equal normal annual rainfall, while Map II. gives the lines of 

 equal normal rainfall for the two periods into which the year is naturally 

 divided, when the rainfall of the parts under consideration is taken as the 

 basis for subdivision, namely, the dry weather (November to May inclu- 

 sive) and the rains (June to October inclusive). It will be noted, on 

 reference to the first of these maps, that Sukkur has an annual fall of 



