﻿354 MR. G. BENTHAM ON THE MIMOSEJ?.. 



tropical, with limited areas ; but the great mass of the species are either widely spread 

 over tropical America, chiefly east of the Andes, or are more local in southern Brazil and 

 adjoining districts. In Africa, besides 2 species, an aquatic Neptunia and a Mimosa, iden- 

 tical with American ones, there are only 2, both belonging to the Mimos(B {BuUcaules), 

 and almost representative of American ones. The Mascarene islands have a very distinct 

 Desmanthus, which might almost rank as a subgenus, and 5 species of Mimosa, all 

 belonging to the same group of BtiMcaules, but some of them rather more distinct than 

 the Asiatic and African ones. In Asia, besides the aquatic Neptunia identical with the 

 African and American one, there is a rather distinct endemic species of that genus, and 

 2 of Mimosa (BuUcaules), both closely representative of American ones. In Polynesia 

 there is a Leuccena, distinct from, but not very far removed from, an American one, and 

 the only Old- World representative of that West- American genus. In Australia the sole 

 members of the tribe are 2 species of Neptunia, forming a section distinguished from the 

 rest of the genus by the reduction of the stamens to a single instead of a double series, a 

 character not observed in any other Old- World Mimosese, and repeated only in the 



American subgenus Uumhnosa. 



As a whole, the Mumimosece, although evidently very early established in the Old 

 World, with the presumably Mascarene or African centre of the suborder, have with 

 difficulty maintained their ground there, whilst in America they have prospered and 

 acquired enormous dimensions. The few exceptional species of the tribe, with more or 

 less prominent glands to the anthers, belong to the small scattered genus Neptmiia, 

 which, however, in other respects, is closely connected with Mimosa. 



The Acacia tribe differs from all the preceding in its comparative prosperity in the 

 Old World, and especially in its wonderful development in the southern hemisphere, in 

 Australia, and to a certain degree in South Africa ; but in both cases the progress seem? 

 to have been from the tropics southward, as there is no trace of the genus in the extreme 

 south of America, nor in T^ew Zealand, nor any connexion between the extratropical 

 African and Australian species. The former belong to a widely spread tropical subgenus, 

 the latter to three specially Australian, subgenera, of which one only has remained 

 sparingly persistent in the Mascarene, Malayan, or South Pacific islands. I would observe 

 that, geographically, I here speak of these divisions of Acacia as subgenera, because they 

 appear to me, in a genealogical sense, to have the same importance as the subgenera oi 

 Mimosa, Fithecolobium, and others, although, being distinguished by vegetative characters 

 only (chiefly foliage and inflorescence), to the utter neglect of numerous floral or carpo- 

 logical differences, they are, for systematic purposes, under the rules usually followed, 

 treated as series only, with adjective instead of substantive names. 



The three extra- Austral ian subgenera are all American; one, a very small one, tne 

 FiliciruB, is endemic and of limited range in Central America, Mexico, Texas, and the 

 West Indies ; but its two species appear to be abundant within their areas, and so 

 variable as to have been described under some eiffht or ten different names. The Ame- 

 rican preponderance is also maintained in the Vulgares, with 42 species, the majority oi 

 which are tropical, with their chief seat in the forest regions east of the Andes, some of 

 them widely spread, very variable, and having Old- World representatives. But there 



