﻿344 MR. G. BENTHAM ON THE MIMOSE^. 



altliough the evidences of their transmission are not so positive as in the case of the two 



first-mentioned species. 



The Mimosese really common to the New and the Old World, without any evidence of 

 modern transportation, or any reasonable doubt as to their having been established in 

 both hemispheres, are, I believe, only four — Bntada scandens, Neptunia oleracea. Mi- 

 mo8a m^erata, and Acacia fame siana. 



Entada scandens varies from a trailing shrub to a gigantic climber, well known for 

 its enormous sabre-like pods. It is widely spread over tropical Asia, and especially 

 abundant in some parts of tropical Africa, and is also said to be frequent in several of 

 the "West-Indian Islands, as well as in the Isthmus of Panama and other parts of Central 

 America, but scarcely extends into South America, except perhaps in a few places along 

 the northern coast. It is a very distinct though variable race, no other species being 

 closely allied to it. The genus is common to South America and tropical and south- 

 eastern Africa ; the species most numerous in the latter continent, and amongst them are 

 those which, upon the whole, approach the nearest to the U. scandens. It might be con- 

 jectured, therefore, that this species had its origin either in eastern tropical Africa, or in 

 that extent of land, now submerged, which many naturalists suppose to have extended 

 far to the eastward of tropical Africa ; and it may at some time have been carried out to 

 the West Indies, although no means of transport previous to the discovery of America 

 have been suggested. The species is sufficiently prevalent near the coasts for its seeds 

 to find their way into the sea ; and the sea will certainly carry them (possibly with 

 masses of sea-weed) to great distances. They are occasionally thrown up on the shores 

 of Britain, and those thus cast up have been made to germinate ; but this is only one of 

 many instances of drifts having been brought by the gulf-stream from the West Indies 

 to the North European coasts ; none that I know of are recorded of drifts from Africa 

 reaching the West Indies. This wide geographical disseverance of JEntada scandens (of 

 which Gyrocarpus Jacquini affords another instance) remains to be accounted for. 



Neptunia oleracea is an aquatic plant whose floating stems root at the joints, and 

 spread rapidly in any slow-running tropical river or large piece of fresh water into which 

 they may have been introduced. It was found abundantly in tropical waters by the 

 early botanical explorers of South America, as well as of tropical Asia and Africa. The 

 genus has several species in extratropical North America, in tropigal Asia, and in Aus- 

 tralia; but these belong severally to three groups, distinct from the N. oleracea \ the 

 only species really nearly allied to it is the terrestrial N. plena j abundant in South Ame- 

 rica, but perhaps, as above mentioned, a colonist only in the Old World, where it is 

 scarce. We might conclude, therefore, that N. oleracea is a species of South-American 

 origin, carried over perhaps in comparatively ancient times by some of those agencies 

 which are known to facilitate the dispersion of aquatic plants, although they have not 

 yet been fuUy investigated. 



Miniosa asperata is a very common weed, if such a word can be applied to a tall 

 shrubby plant, over the greater part of South America, where it passes almost gradually 

 into more than one allied species, and which is also the country of the whole group to 

 which it belongs. It may therefore be concluded with but little hesitation that it is of 



