PEEFAOE. 



The area dealt with, in this Flora amounts approximately to 

 196,000 square miles. It is bounded on the north and north-east hy 

 % portion of the main chain of the Western Himalaya, and on the 

 mst by Bengal. On the south and south-west the boundary follows 

 ^ watershed, from which all the rivers west of the Son, and flowing 

 • the Ganges and Jumna from these directions, take their rise. 

 e watershed extends along the northern slopes of the numerous 

 jjioups of hills known collectively as the Vindhya mountains, and 

 which separate the Gangetic Plain from the Narbada Valley. Mount 

 AV u, a solitary outlier of the Aravalli Hills, and rising to 5,653 feet 

 ftlxve the sea, is not included. The area, thus defined, contains the 

 whole of the Upper Gangetic Plain as far as the confines of Bengal, 

 also the Siwalik range of hills, and the Sub -Himalayan tracts from 

 the Jumna to the Gandak. The large piece of country lying to the 

 8o;ith'west of the Gangetic Plain proper includes a portion of Baghel- 

 khand in Central India, also Bundelkhand, the Malwa plateau, East- 

 nr Rajputana, and a small piece of the W. Punjab in the neighbour- 

 h:. i of Delhi. In thus attempting to secure a satisfactory geographi- 

 m- area, it was impossible to avoid clashing with political boundaries. 

 Il f'ill be noticed, however, on referring to the map, that all the 

 districts of the United Provinces of Agra and Oadh south of the 

 Himalaya are represented. The inclusion of Dehra Dun, ' as well as 

 of other portions of the submontane tracts of Garhwal, Kumaon and 

 Nepal, may be objected to as being an encroachment on the Himalayan 

 j'e'^'on, but the difficulty was to find any continuous and workable 

 Tidary line outside the base of the Himalaya proper. It should 

 be borne in mind that a writer of a Flora of the Western 

 ualaya might not be willing to take these particular tracts into his 



