GENERAL REPORT. 5 



which they possess under the double guard of villosity and contraction. I 

 am aware that Mr. Watson, in his most valuable report on the Botany of 

 the Fortieth Parallel, is prepared to admit a large evaporation from the 

 more succulent portions of the plant. 



The monotonous character of the flora of the drier regions does, in 

 some measure, disappear, when, on examination of these plants, so uniform 

 in general appearance, we find a large number of genera and species differ- 

 ing from one another by the small amounts compatible with their surroundings. 

 This (the surroundings) in part accounts for the predominance of some 

 orders and often of genera. We find a somewhat similar condition of things 

 in the centre of greatest development of the Proteacece in Australia, or of the 

 Pelargoniums in South Africa. 



Comparatively few of our Eastern plants are found in these open grounds, 

 and where one does occur it is apt to be a cosmopolitan weed, whose pliant 

 constitution adapts it to any condition of life, as well as to the hostility of 

 man. Polygonum aviculare-and Chenopodium hybridum are examples. Among 

 the exceptions to this statement is Ranunculus Cymbalaria ; but its natural 

 habitat on the Western open lands is, by choice, alkaline soils, where, for a 

 portion of the year at least, it can obtain moisture, just as with us it fre- 

 quents salt-marshes and the sea-shore. 



Among the mountains, on the contrary, we find a larger number of 

 familiar plants. Indeed, the list is so large that it would be a real labor to 

 begin the enumeration. Those plants embraced under the common name of 

 weeds are from necessity found usually on the roadsides and about habita- 

 tions, just where they can be transported by human agency, and find, among 

 other essentials, water. It is wonderful with what rapidity they have occu- 

 pied the ground in many places. 



FLORA OP THE MOUNTAINS. 



Leaving the level ground, we at once come fairly within the range of 

 the timber In South Park, this is not far from 10,000 feet altitude : tongue- 

 like projections of trees do extend lower down ; but I refer to the main body 

 of the forests. 



At Twin Lakes, the timber begins at about 9,500 feet. In the San Luis 



