THE CARDOON 125 



North America, where coarse grass, between five and six feet 

 high, 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 occurring 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 preferer les 

 chemins, et le bord des routes pour deposer leurs excremens, 

 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 con- 

 tinents I saw it in unfrequented spots in Chile, Entre Rios, and 

 Banda C/Fiental. In the latter country alone, very many (prob- 

 ably 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. 



2 M. A. d'Orbigny (vol. i. p. 474) says that the caidoon and artichoke are both 

 found wild. Dr. Hooker {Botanical Magazine, vol. Iv. 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 cardoon ; 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 difterent from the cardoon ; and 

 more hke a thistle properly so called. 



