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Botanical Geography. | i og be 
_ the arborescent vegetation. The climate is not, however, in | 
- . itself unfavourable to the growth of trees, as is the case with 
_ the prairies and the steppes of the Old World. In Uruguay | 
generally the cultivation of trees is possible ; in Buenos 
__ Ayres the peach is grown for the sake of its wood. 
The Pampas-region may be divided into three zones :— 
the interior north-western Chanar-steppe ; the true Pampas; 
and the southern plains of Patagonia. The first is not oc- 
cupied to any great extent by grass, but is chiefly covered 
by underwood, especially the chanar-shrub, an Acacia known 
as ‘espinillo,’ and species of Cactus. At the foot of the 
Andes it includes some salt lowlands, the Argentine 
‘salinas,’ where the vegetation consists of only a few saline 
plants. The true Pampas are grass-plains, in which the 
trees are confined to narrow strips of low woods along the 
rivers. ‘There are scarcely any native shrubs or herbaceous 
plants ; but some from the south of Europe have become 
naturalized ; thistles and fennel have increased to an enor- 
mous extent ; Onopordon acanthium has entirely displaced the 
grass over many square miles, and forms impenetrable 
thickets, exceeding a man’s height. Where the grass-steppe 
Vir Py AF 
ceases, at the Patagonian Colorado and Rio Negro,alow, | 
‘sparse, thorny, shrubby vegetation begins, growing among 
louse stones, until at length this also becomes scarce, and 
the arid ground, parched by the dry air, produces only a 
few tufts of a hard brown grass. A small Acacia, which is 
- found alone and solitary in the neighbourhood of the Rio 
Negro, is so remarkable a phenomenon to the natives that it 
is regarded as sacred. | 
22. The Chilian Transition- Region. 
This region, which includes the northern and central 
provinces of Chile, enjoys a climate similar to that of the 
Mediterranean ; but the season of active growth is interrupted 
by longer periods of drought ; for during one-half of the 
