iv TROPICAL FLORAS 43 



will equal, those of tropical America, or even of tropical 

 South America only. Portions of this area have been well 

 explored, especially the great peninsulas forming India 

 proper, Burma, and Indo-China ; but the two latter are only 

 sufficiently known to show their extreme richness botanic- 

 ally, and the same may be said of the numerous large 

 islands of the Malay Archipelago. We may, I think, be 

 certain that what is known of these two sub-regions is less 

 than what remains to be made known. 



Sir Joseph Hooker estimates the whole flora of British 

 India at 17,000 species, including the desert flora of the 

 Indus valley and the rich temperate and alpine floras of the 

 Himalayas above an elevation of 6500 feet in the east and 

 above 4000 or 5000 in the west But as I am here dealing 

 with tropical floras, it is only necessary for me to give such 

 figures as are available for the specially tropical portions 

 of it. 



The Indian Peninsula, bounded on the north by a curving 

 line of hills and mountains which run not far from the line 

 of the geographical tropic, is somewhat poor when compared 

 with the abounding riches of Burma and Indo-China ; yet it 

 possesses areas, especially in the Western Ghats and the 

 Nilgiris, of great botanical richness and beauty, much of 

 which is still inadequately explored. Arid conditions pre- 

 vail over much of its surface, both in the north and in the 

 central plains, but these are interspersed with deep moist 

 valleys containing a vegetation allied to that of Assam. As a 

 result of this greater aridity than that of the countries farther 

 east, the peninsula is much poorer in Orchids, having only 

 200 species against 700 in Burma ; but it has a great excess 

 in Grasses, Umbelliferae, Labiatse, and Boragineae, and a 

 corresponding poverty in Melastomaceae, Gesneraceae, Myr- 

 tacese, Palms, and other more peculiarly tropical orders. 



Ceylon, though so closely connected with the peninsula, 

 has a distinct flora, nearly 800 of its species and 23 of its 

 genera being "endemic," that is, wholly peculiar to it. It 

 has much stronger affinities with the Malayan flora, due in 

 part, no doubt, to its moister and more uniform insular 

 climate, but also to some features of its past history. 



The figures given in the table of the chief tropical floras 



