AND THE NEIGHBOURING DISTRICTS. 197 



(Enotherece (Endl.). — Of the four principal genera of this family, Jussicea, Oenothera, 

 Epilobium and Fuchsia, the Argentine region possesses only the first two. Some species 

 of Jussicea are plentiful on the marshy shores of the Plata, hut as the genus has its head- 

 quarters within the tropics, so it is richer in species at Porto Alegre than at Buenos 

 Ayres. Prom this latter place I possess three species of (Enothera. Fuchsia, so charac- 

 teristic of the west side of South America, seems, on the eastern side, to be confined to 

 tropical Brazil. 



Melastomacecc. — One species only (as I have already mentioned) extends as far south 

 as the Rio de la Plata, hut does not appear on the southern bank of that river. Even in 

 Rio Grande, the plants of this order are few when compared with their abundance in 

 tropical Brazil, and when compared also with the allied family of Myrtles. I am aware of 

 only nine species from the southern extremity of Brazil. 



Leguminosce. — The Argentine region is not particularly rich in these plants ; at least, 

 they by no means form so important a part of the vegetation as in tropical Brazil, in the 

 south of Europe, or in Australia. The Leguminosce of the region in question belong, with 

 few exceptions, to genera widely diffused, such as Crotalaria, Lupinus, Tephrosia, Indigo- 

 fera, Desmodium, JEschynomene, Lathyrus, Clitoria, Cassia, Mimosa, Inga, Acacia. This 

 is quite a contrast to what is observable at the Cape of Good Hope, where the number of 

 peculiar or endemic genera of this order is remarkably great. The observation which I 

 have already made, as to the small number of peculiar forms in the Argentine Plora, when 

 compared with that of the Cape, is particularly exemplified in this important family. The 

 same holds good, perhaps in a still greater degree, if we compare it with the Plora of corre- 

 sponding latitudes in Australia. It may be observed, also, that the greatest part of the 

 Leguminosa? of the Plata belong to genera which are principally tropical, and which only 

 straggle, as it were, into cooler latitudes ; such are all but two, or perhaps three, of the 

 genera mentioned above, One is almost tempted to say that the vegetation of this region 

 is a mere modification, a reduced or dwindled form, of the Brazilian, instead of being a 

 separate and strongly marked Plora like that of the Cape. 



Again, at the Cape, the Lotece predominate remarkably over the other papilionaceous 

 tribes ; in the region of the Plata, the Hedysarece and Fhaseolece are at least equally 

 numerous. Ccesalpinece and Mimosea? are more numerous on the banks of the Plata than 

 in the same latitudes in South Africa. In that country, south of the Orange River, I 

 know of only two species of Acacia, although these are so abundant (one of them espe- 

 cially) as to give a distinctive character to the scenery ; nor, as far as I am aware, are 

 there any other Mimosece south of the same river, although, to the north of it and at 

 Natal, (about the latitude of the southern extremity of Brazil,) they become numerous. 

 Mr. Pox's collections from Buenos Ayres and Uruguay (between 33° and 35° S. lat.) 

 include five species of Mimosa, one of Desmanthus, two of Calliandra, and five of Acacia ; 

 yet none of these are so abundant as to form characteristic features of the country, like 

 the Acacia horrida and Caffra in the eastern part of the Cape colony. The Ccesalpinece 

 of these latitudes are principally Cassia, of which there are several species at Buenos 

 Ayres. The magnificent Foinciana Gilliesii is said not to be indigenous there, though 

 now well established on the banks of the Plata. 



