222 jLinnean Society. [May 3, 



ence in the structure of its banks, the Plata does not form a botani- 

 cal boundary. There are indeed several species of plants which are 

 confined to one side or the other, and some families (principally 

 tropical) which do not cross it ; yet the leading characteristics of 

 the vegetation, both as to its general physiognomy and its prevailing 

 forms, are the same on both sides. The whole country, therefore, 

 from the frontier of Brasil southward, as far as the Pampas vegeta- 

 tion extends (or to the border of Patagonia), may be considered as 

 one botanical province, which, for the sake of convenience, Mr. 

 Bunbury provisionally calls the Argentine region, from the name of 

 the great river. 



The botanical characteristics of this region are well-marked ; its 

 most striking peculiarity consists in the almost entire absence of 

 trees, and the scarcity even of shrubs except along the banks of the 

 principal rivers. Every one who has come from Rio de Janeiro to 

 Monte Video and Buenos Ayres has been struck by the contrast 

 between the gigantic vegetation of Brasil and the bare, treeless, 

 almost barren character of the shores of the Plata, where the culti- 

 vated Poplars, and the flower- stalks of the Agave, with here and 

 there a solitary Ombii tree {Phytolacca dioica), are the only objects 

 that relieve the nakedness of the country. It is not that the vege- 

 table covering of the soil is really scanty ; but the vast majority of 

 the plants which compose it are herbaceous, of low growth, and for 

 the most part not very conspicuous. This treeless character has 

 been forcibly described, and its possible causes most ably discussed, 

 by Mr. Darwin in his ' Journal.' The immediate banks of the Uru- 

 guay and Parana, however, and the islands in those rivers, appear 

 to be wooded, although not with trees of great height or size. As 

 compared with Brasil, the vegetation of the Argentine region is 

 further distinguished (as might be expected) by the diminished num- 

 bers of tropical families, and also by something of a more European 

 physiognomy. The resemblance in this particular appears, however, 

 to Mr. Bunbury to be not so great as has been represented, being in 

 a great measure due to the abundance of naturalized European 

 plants ; and excluding these, to consist rather in a certain general 

 similarity of character than in a real botanical analogy. Schouw's 

 estimate, that out of 109 genera which belong to Buenos Ayres, 

 70 appear in Europe, and St. Hilaire's statement, that of 500 spe- 

 cies collected by him in the Banda Oriental, only 15 belonged to 

 families completely strangers to Europe, are doubtless accurate so 

 far as they go ; but the vegetation of these countries is really more 

 different from the European than such comparisons would seem to 



