XXvi . INTRODUCTION. 
Comparing the number of endemic species of the Indian Flora with that of other 
parts of the world, it is somewhat surprising to discover that it is less than 2 per cent. 
below the Mexican, and not far below that of the Australian; being no less than 
68°67 per cent. But such statistics embrace only one class of facts, the value of which 
will be briefly discussed in connection with the delimitation of the primary botanical 
regions. 
ON THE DISTRIBUTION OF SOME OF THE LARGEST NATURAL ORDERS. 
Attention has already been directed to the illusory nature of mere statistical com- 
parisons of the vegetation of different regions. In many Floras the orders richest in 
species are not those which give character to the scenery, or constitute the bulk of the 
vegetation ; and the genera are sometimes less numerous and less diversified than those 
of many concomitant orders less numerous in species. This is pre-eminently the 
case with the orchids in India. Many of the species are exceedingly rare and local ; 
many are small plants with inconspicuous flowers; and the comparatively small number 
of common species having large conspicuous flowers, lend colour to the vegetation 
rather than give character to it, and this only in certain districts. Here and there 
in the mountains, as we learn from travellers and residents, the rocks are clothed 
with orchids, and when they are in full flower form a conspicuous feature in the land- 
scape. In South Mexico and Central America orchids, though third in order of 
predominance, pervade the whole country to a greater extent; yet here, as elsewhere, 
the existence of the preponderating epiphytic species depends largely on the arboreous 
vegetation. In Northern and Eastern India and Malaya, as in Mexico, orchids are 
specially abundant in the intermediate or oak region, and the numerous species of 
oak constitute one of the principal features in the vegetation. Lower down in the 
more tropical parts of India arboreous Leguminose, Euphorbiacee, figs, laurels, 
Dipterocarpee, Anonacee, together with Rubiacee, Acanthacee, Composite, Scita- 
mine, Aroidee, &c., constitute the bulk of the vegetation—some of these orders, 
their genera, or even species predominating in one district, some in another; but each 
or any of them entering more fully into the composition of the vegetation than orchids. 
Palms form a conspicuous feature on the coast and plains of India, where the more 
or less cultivated coco-nut, the palmyra (Borassus), and Phenix sylvestris abound and 
cover large tracts; but there is little variety in the prominent species; and the order 
occupies the thirtieth position only by reason of the large number of species of rattan 
(Calamus) that inhabit the dense forests, and render them almost impenetrable. 
Nowhere is there anything resembling the highly diversified palm-groves of the 
Amazon region. 
In Mexico the Composite outnumber the order next in sequence by upwards of 100 
genera and 500 species, and although few of them exceed the stature of shrubs, they 
grow in almost every variety of situation; are often excessively numerous individually ; 
