1833.] * THE CARDOON, | 119 
when grazed by cattle, changes into common pasture land. I 
am not botanist enough to say whether the change here is owing 
' to the introduction of new species, to the altered growth of the 
same, or to a difference in their proportional numbers. Azara 
has also observed with astonishment this change: he is likewise 
much perplexed by the immediate appearance of plants not oc- 
curring in the neighbourhood, on the borders of any track that 
leads to a newly-constructed hovel. In another part he says,” 
“ ces chevaux (sauvages) ont la manie de préférer les chemins, 
et le bord des routes pour déposer leurs excrémens, dont on trouve 
des monceaux dans ces endroits.” Does this not partly explain 
the circumstance? We thus have lines of richly-manured land 
serving as channels of communication across wide districts. 
Near the Guardia we find the southern limit of two European 
plants, now become extraordinarily common. The fennel in 
great profusion covers the ditch-banks in the neighbourhood of 
Buenos Ayres, Monte Video, and other towns. But the cardoon 
(Cynara cardunculus){ has a far wider range: it occurs in these 
latitudes on both sides of the Cordillera, across the continent. 
I saw it in unfrequented spots in Chile, Entre Rios, and Banda 
Oriental. In the latter country alone, very many (probably 
several hundred) square miles are covered by one mass of these 
prickly plants, and are impenetrable by man or beast. Over the 
undulating plains, where these great beds occur, nothing else 
can now live. Before their introduction, however, the surface 
must have supported, as in other parts, a rank herbage. I 
doubt whether any case is on record of an invasion on so grand 
a scale of one plant over the aborigines. As I have already 
said, I nowhere saw the cardoon south of the Salado; but it is 
* Azara’s Voyage, vol.i. p. 373. : 
+ M. A. @Orbigny (vol. 1. p. 474) says that the cardoon and artichoke are 
both found wild. Dr. Hooker (Botanical Magazine, vol. lv. p. 2862), has 
described a variety of the Cynara from this part of South America under 
the name of inermis. He states that botanists are now generally agreed that 
the cardoon and the artichoke are varieties of one plant. I may add, that an 
intelligent farmer assured me that he had observed in a deserted garden 
some artichokes changing into the common cardoon. Dr. Hooker believes 
that Head’s vivid description of the thistle of the Pampas applies to the car- 
doon; but this is a mistake. Captain Head referred to the plant, which I 
have mentioned a few lines lower down, under the title of giant thistle. 
Whether it is a true thistle, I do not know; but it is quite different from the 
eardoon; and more like a thistle properly so called. 
