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 has 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 Composite, 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 + 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 ZEschynomene (Æ. ciliata, Vog.), 
excessively like the North American Æ. hispida; a Pontederia, extremely near to cordata, 
if not a mere variety of it; a Sisyrinchium, 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 er 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 Solanee, Verbenee, Amaranthacee, Calyceraceæ, He- 
lianthoid Composite, Pontederias, Jussieas, Eryngiums, and other forms which make up 
the most important part of the vegetation on the shores of shock Tatas are wanting or 
insignificant at the Cape, which, as is well known, is characterized by Proteas, Heaths, 
Diosning;Pelat goniume, Mesembryanthemums, Aloes, Crassulaceæ, and fiss&acer ; all of 
them absent, or nearly so, from the region of which I here treat. Leguminose are abun- 
dant in both countries, but for the most part of different genera. Almost the only points 
* Journal, 2nd edit. p. 128. + See the Botanical Miscellany, vol. iii. 
