182 TvELATION BETWEEN CLIMATE AND VEGETATION 



the formidable barrier which separates the province of Tomiua 

 from that of Cinti much more easily than I expected. 



I had now to ascend the opposite mountain and to rise almost 

 into the snowy regions. The Avoods which skirt the river are 

 almost wholly composed of Mimosas, and amongst others of a 

 large bush of some species of Ruprechtia, covered with bunches 

 of scarious flowers : a liundred yards higher the region of the 

 Cacti begins, and here I found many of these plants that were 

 quite new to me ; higher still, these made way for others more 

 suited to a less temperate climate — to Gentian, Kanunculi, Cal- 

 ceolarias, and Luzicla ; on the top of the scale were linear- 

 leaved Violets, Umbellifers, stemless Composites (Azorella, 

 Werneria, Trichocline, &c.), and Papilionaceous plants forming 

 a carpet. I had now reached one of those cold pasture lands 

 called Punas, the country of the Vigognes and Guanacos, where 

 there is always a piercing wind, and tlie thermometer descends 

 every night below the freezing point. Notwithstanding the bitter- 

 ness of the climate the country is inhabited. 



The sandstone, which is the principal substance in this part of 

 Bolivia, is here found in immense naked blocks, each of which is 

 a mountain by itself; the vertical sides of these masses, which 

 are formed of perfectly horizontal layers, are divided from top to 

 bottom by deep furrows. 



After travelling for about two days in this cold district, I 

 began once more to descend, and soon found a very remarkable 

 vegetation, composed of spiny shrubs or bushes, rivalling the 

 quantities of Cereus and Melon-cacti which grew upon the 

 surrounding rocks and made them bristle with their formidable 

 spines. Tliere were Berberries, Nightsliades, the Orange-flowered 

 Chuquiraga, Flotovia, and many species of Bugainvillea. 

 Here and there were dense round hillocks of a Bolax (Yareta) 

 covered with resinous tears. But one tree, the Quenua (a species 

 of Polylepis), was to be found here, and it occurred in still 

 higher regions ; its thin cinder-coloured top is supported by a 

 twisted trunk, seldom more than 2 or 3 yards in height ; its 

 red bark divides into thin leaves, which are torn and blown away 

 by the wind. The Indians have no other wood with which to 

 construct their huts, and they are consequently as small as they 

 can be. The doors are made of planks of a sort of Cactus 

 (Carapaci). 



A Mimosa, the branches of which spread out into a large 

 green top, contrasting strongly with the rest of the vegeta- 

 tion of these plains, deserves notice, as it is a bush covering great 

 spaces of ground where its appearance was hardly to be looked 

 for. This is the country for Barley and Potatoes ; the straw 



