THE VOYAGE OP THE BEAGLE 



131 



peach and quince trees. The plain here looked like that 

 around Buenos Ayres ; the turf being short and bright green, 

 with beds of clover and thistles, and with bizcacha holes. 

 I was very much struck with the marked change in the 

 aspect of the country after having crossed the Salado. From 

 a coarse herbage we passed on to a carpet of fine green ver- 

 dure. I at first attributed this to some change in the nature 

 of the soil, but the inhabitants assured me that here, as 

 well as in Banda Oriental, where there is as great a differ- 

 ence between the country round Monte Video and the 

 thinly-inhabited savannahs of Colonia, the whole was to be 

 attributed to the manuring and grazing of the cattle. Ex- 

 actly the same fact has been observed in the prairies 7 of 

 North America, where coarse grass, between five and six 

 feet high, when grazed by cattle, changes into common pas- 

 ture 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 aston- 

 ishment this change: he is likewise much perplexed by the 

 immediate appearance of plants not occurring in the neigh- 

 bourhood, on the borders of any track that leads to a newly- 

 constructed hovel. In another part he says, 8 " 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 dis- 

 tricts. 



Near the Guardia we find the southern limit of two Eu- 

 ropean plants, now become extraordinarily common. The 

 fennel in great profusion covers the ditch-banks in the neigh- 

 bourhood of Buenos Ayres, Monte Video, and other towns. 

 But the cardoon (Cynara cardunculus) has a far wider 

 range: 9 it occurs in these latitudes on both sides of the 



\ See Mr. Atwater's account of the Prairies, in Silliman's N. A. Journal, 

 vol. 1. p. 117. 



8 Azara's Voyages, vol. i. p. 373. 



8 M. A. d'Orbigny (vol. i. p. 474) says that the cardoon 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 botanist* are now generally 



