the Vegetation of a Country. 44)5 



2. Certaiu fainilies are characteristic by being peculiar to the 

 region under consideration, or at least presenting a greater pro- 

 portion than in other regions, either with regard to the Pha- 

 nerogatnia of the same region or to the species of each family. 

 Thus, the Berberideae are characteristic of Chili; the Stylidieseof 

 New Holland ; the llesedacese of the Mediterranean and adjacent 

 region ; the Cactaceaj of Mexico ; and the Oxalideai of Brazil 

 and of the Cape ; &e. 



The total or nearly total absence of a family in a region, espe- 

 cially when the conditions of climate might lead one to expect 

 that it would occur there, is also a character that must not be 

 neglected. 



Lastly, the combination of the families deserves notice, as weil 

 as the characters belonging to each in particular. Thus, the 

 vegetation of the island of Juan Fernandez, consisting essentially 

 of Compositae and Ferns, must present a very different aspect to 

 a vegetation in which the Compositae are associated with the 

 Leguminosae, or the Ferns mixed with Aroidese or Orchidcte; and. 

 as the principal families combine by threes, fours, &c.. Floras of 

 excessively various characters are produced. 



3. Characters relating to the Genera. 



The indication of the genera which include the greatest 

 number of species, or which are most apparent from the number 

 of individuals, is also a mode of depicting the ensemble of the 

 vegetation of a country, to which many, even superficial, travellers 

 have paid attention. Unfortunately this character is not sus- 

 ceptible of great precision, and is applied with difficulty to the 

 comparison of one country w ith another in consequence of the 

 multitude of genera, the want of a complete enumeration of the 

 species of many regions, and the great number of genera which 

 occur in two or more adjacent or even distant regions. 



Here, as with the families, we may remark i\\e predominating 

 and the characteristic genera. 



4. Characters relating to the Species. 



The presence of a species in a country is always a character 

 in itself, but the number of the species is so great, that it is im- 

 possible to attend to all the facts of this nature. It is sufficient 

 in general to ascertain, — 



1. The commonest indigenous species, paying particular atten- 

 tion to the trees and to the species which predominate in the 

 principal stations of the region under consideration. 



2, The remarkable and characteristic species, that is to say, 

 more or less abundant in the country, but of a nature to strike 

 a botanist, and not existing in the neighbouring countries. 



