192 MR. BUNBURY ON THE VEGETATION OF BUENOS AYRES 



in the Argentine Flora which strongly remind us of South Africa, are several species of 

 Oxalis, and some gay -flowered Iridece and Amaryllidece ( Cypella Herberti, Sisyrinchium 

 Bonariense, species of Habrcmthus and Zephyr writhes), which decorate the hanks of the 

 Plata. The Cactece of the latter country are represented at the Cape hy succulent 

 Euphorbias ; and the herbaceous and half-shrubby Malvaceae, which are numerous at 

 Buenos Ayres, have South African representatives in the Hermannice. 



Another thing which strikes us when we compare the Flora of Buenos Ayres with that 

 of the Cape of Good Hope is, that the former is much less peculiar in its character than 

 the latter. The Argentine region, considered botanically, is recognized at once as a pro- 

 vince of South America ; all its characteristics are such as belong especially to that part 

 of the world, while the botany of the Cape has little resemblance to that of the rest of 

 Africa. The distinction will be very apparent, if we compare, on the one hand, the Flora 

 of the Plata with that of tropical Brazil, and on the other, the Cape Flora with that of 

 tropical Africa. The number of peculiar or endemic genera of plants in the Argentine 

 region is comparatively very inconsiderable ; at the Cape, remarkably large. The pecu- 

 liar genera of the former region almost always consist of a single species, or of very few ; 

 several of the peculiar Cape genera are very rich in species. The number of species com- 

 mon to the shores of the Plata and the tropical parts of the same continent is considerable, 

 while extremely few are common to the Cape and tropical Africa. 



A part of these differences may be accounted for by the local circumstances of the two 

 countries. The Cape of Good Hope, as a botanical region, is almost cut off from the rest 

 of Africa by the great deserts which, to the north of the Orange Biver, stretch across so 

 great a part of the continent. Even in the colony itself, the desert called the Great Kar- 

 roo is known to set an absolute limit to the northward extension of several characteristic 

 families *. Now there is no barrier of this sort on the eastern side of South America, 

 where (excepting perhaps the case of Patagonia) the limits of the range of plants seem to 

 be fixed by climate alone. Moreover, it is probable that the characteristic Cape plants, 

 generally speaking, are of a more delicate constitution, and have less power of bearing 

 change of circumstances, than those of Buenos Ayres ; as may be inferred from the much 

 greater difficulty of cultivating them in gardens. 



Another difference that I may notice, between the Cape of Good Hope and Buenos 

 Ayres, is that naturalized European plants do not play by any means so conspicuous a part 

 in the botany of the former country as in that of the latter. A good number of introduced 

 species have indeed established themselves in the neighbourhood of Cape Town, but they 

 have not spread far, nor do they appear in any remarkable quantity, nor at all vie with 

 (much less supersede) the original natives of the soil. It is not owing to the greater 

 extension of European culture that these plants have been more widely diffused in the 

 region of the Plata ; for although a great part of that country might probably be found 

 very fit for cultivation, the proportion of it which has actually been brought into that 

 state is very minute indeed. The climate, from its greater moisture, may be more favour- 

 able to such plants than that of the Cape, but the chief cause of the difference is probably 

 to be found in the soil, 



* See Burchell's Travels. 



