172 



DISTRIBUTION OF PLANTS. 



Lichens. Abundantly intermingled with the Tillandsias, and of the same grey color; 

 together forming beds that overspread the Desert mountain-summits. There seemed, 

 however, to be very little variety in species, and only three or four genera. 



Fungi. Seemed extremely rare, at least, the larger species. They did not, however, 

 receive special attention ; and were not very diligently searched for. 



3. The Peruvian Mountain-region, on the Slope of the Andes. 



On the morning of the 18th of May, oiir party left Yaso, journey- 

 ing Eastward along the river ; and were first made aware of tlie enor- 

 mous depth of the valley in which we were travelling, by our guide 

 pointing out above us the village of St. Joseph's. Though only half- 

 way up the steep acclivity, the village seemed but a speck, to most of 

 our party for a long time indistinguishable. 



The mountain-heights forming the sides of the valley, were no 

 longer uniformly grey ; but on their upper portion were distinctly 

 tinged with green. Two leagues from Yaso, they were greenish to 

 the base; and an Agave? made its appearance; in clusters of huge 

 bayonet-shaped leaves around a central flower-stem twenty feet high, 

 stationed at intervals in rocky places as far up as the eye could 

 reach ; a striking introduction to a new botanical region. 



The sudden change in the buildings from flat to inclined roofs also 

 indicated, that we were entering a district subject to rain. A regular 

 "rainy season" was in fact spoken of; that the rains are scanty, or 

 with periods of drought intervening, appeared afterwards from the 

 absence of trees and forest-growth throughout this mountain-region. 



As our party proceeded, the distinction between the vegetable growth 

 on the upland and in the infiltrated ground, disappeared. Grasses 

 became frequent, and were spread over the whole face of the country; 

 with an accompanying universal freshness unknown in rainless 

 districts. The cane-brakes ceased, the bottom of the valley being 

 narrower; and the ascent soon becoming steep, there was no longer 

 room for marshes ; the few wet-ground plants present, being confined 

 to the immediate margin of streams. 



Shrubs in considerable variety were frequent, and even somewhat 

 luxuriant; but nowhere growing in tangled thickets; and tree-UA-e 

 plants were met with of the height of shrubs, the trunk very large, 

 dividing above into a few stout spreading branches. 



