AND THE NEIGHBOURING DISTRICTS. 191 



Porto Alegre ; but the fact mentioned by M. de St. Hilaire *, that the cultivation of man- 

 dioca and sugar extends so far south, and no further, seems to point it out as the southern- 

 most limit of the seasons of tropical Brazil. Mr. Darwin lias remarked the rapid change 

 of climate in proceeding northward from Buenos Ayres, and in accordance with this, appa- 

 rently, is the change of vegetation. 



It would be interesting to compare the Flora of Chile with that of the Argentine region, 

 but for this I have not sufficient materials. Meyen, in his • Geography of Plants,' says 

 that Chile and the countries on the eastern side of the Andes, in corresponding latitudes, 

 cannot be considered as separate botanical regions ; yet the information which he himself 

 gives, in the same work, as to the Chilian Flora, seems to show that its general physio- 

 gnomy is very different from that of the Argentine region. The accounts of many tra- 

 vellers show us that the climate and soil of Chile, in the latitudes of which I treat, are 

 much more dry than those of the countries near the Plata, and this cannot fail to be 

 attended with a considerable difference in the vegetation. The Chilian Flora, by Meyen's 

 account, appears to be as strikingly characterized by dry shrubs with coriaceous and 

 glossy leaves, as that of the Plata is by the prevalence of herbaceous forms. In the 

 abundance of Myrtles, indeed, and of shrubby and arborescent Composites, the vegetation 

 of Chile may be compared rather with that of southern Brazil. At the same time, the 

 valuable catalogues drawn up by Sir W. Hooker and Dr. Walker- Arnott t show that many 

 remarkable genera, and not a few species, are common to both sides of South America. 



The Argentine Flora has little or no general analogy to that of the southern parts of 

 North America lying in corresponding latitudes on the other side of the equator ; yet 

 there are some striking, though insulated, points of resemblance. There is a species of 

 Cephalanthus on the shores of the Plata ; there is an JEschynomene {JE. ciliata, Vog.), 

 excessively like the North American JE. hispida ; a Pontederia, extremely near to cordata, 

 if not a mere variety of it ; a Sisyrmchium, much resembling S. Bermudianum. 



If we compare the Flora of the shores of the Plata with that of the Cape of Good Hope 

 lying within the same parallels of latitude and having nearly the same mean temperature, 

 we find an extraordinary difference between them. The many points of analogy, and the 

 general physiognomical resemblance, between the vegetation of the Cape and of New 

 South Wales have repeatedly been noticed ; but between the botany of the Cape and that 

 of La Plata we find scarcely anything but contrasts. It is not easy to discover any points 

 of resemblance. The general physiognomy of the vegetation is different : the plants of 

 the Argentine region are chiefly herbaceous, while at the Cape there is a great predomi- 

 nance of dry, hard, small-leaved shrubs. Almost all the characteristic families and genera 

 of the two Floras are different : the Solanece, Verbenecs, Amaranthacecs, Calyceracece, He- 

 lianthoid Composites, Pontederias, Jussicsas, Eryngiums, and other forms which make up 

 the most important part of the vegetation on the shores of the Plata, are wanting or 

 insignificant at the Cape, which, as is well known, is characterized by Protects, Heaths, 

 Diosmas, Pelargoniums, Mesembryanthemums, Aloes, Crassulacea, and Restiacea? ; all of 

 them absent, or nearly so, from the region of which I here treat. Leguminosa are abun- 

 dant in both countries, but for the most part of different genera. Almost the only points 



* Journal, 2nd edit. p. 128. f See the Botanical Miscellany, vol. iii. 



