BOTANY. 15 



along the river, and on the hills which horder it, are found many plants not met with below. 

 Of the trees, Q. Hindsii, Q. Garryana, and Q. Agrifolia, the "nut pine," and cotton-wood, were 

 the most common. Among shrubs, on the higher lands, were the Manzanita, Fremontia, and 

 Ceanothus cuncatics, here forming thickets ; near the river bank, Cephalanthus occidenlalis, Cercis 

 occidentalis, Calycanthus occidentalis, Eriodictyon glutinosum, Rhus diversiloba, Alnus viridis, 

 and Alnus Oregana, the latter forming a tree fifty feet in height. 



BOTANY OF SIERRA NEVADA. 



The Sierra Nevada, with its continuation, the Cascade range of Oregon, forms a distinct 

 botanical district, characterized not only by the presence of many plants not found on the Coast 

 Range or in the valleys, but by the prevalence of certain species throughout this entire mountain 

 system. Its general altitude and the peaks, which, at many points, rise high above the line of 

 perpetual snow, give an Alpine character to much of its vegetation, even in a low latitude. 

 From the observations of many botanists who have crossed the Sierra Nevada in southern Cali- 

 fornia, we learn that the different zones of vegetation which mark the different grades of altitude 

 include many plants which, on the less elevated surfaces, are separated by several degrees of 

 latitude. Of these, the Douglas spruce, the western balsam fir, and several other trees which 

 compose a large part of the forests covering the banks of the Columbia, extend at a higher 

 elevation quite to the northern line of Mexico. The number of these widely distributed species, 

 among which should also be included very many annual plants, gives a unity of character to 

 the botany of this mountain range which requires it to be regarded as a distinct botanical 

 district. The influences which have most contributed to form or modify this flora are probably 

 to be found in the continuity and the uniformity of geological structure and altitude of this 

 mountain system, the similar relations which its different parts hold to the ocean from which 

 they derive the marked similarity of their climate. 



The western slope of these mountains receives a copious precipitation from the winds coming 

 in from the Pacific over the coast ranges and the valleys. As a consequence, it is generally 

 clothed with a dense forest. This forest is composed almost exclusively of coniferous trees, 

 and, with the exception of the red-wood, includes all those gigantic forms of vegetation so 

 characteristic of the botany of western America. On the western slope of the Sierra Nevada, 

 in California, is found the famous group of Sequoias, which, from their unequalled magnitude, 

 have very properly received the name of gigantea, in common language only known as the 

 "mammoth trees." The yellow pine, (P. Ponderosa,) the sugar pine, (P. Lambertiana,) the 

 western balsam fir, (Picea grandis,) and (Libocedrus decurrens,) comprise the greater part of the 

 forests which cover this slope as far down as the latitude of San Francisco ; the yew, (Taxus 

 brevi/olia,) and two species of cypress, (C. nuthatensis and 0. Lawsoniana,) being also occasion- 

 ally met with. Among the foot hills, at a lower level, the nut pine mingles with the oaks, 

 reaching up to the pine forests above, but scarcely forming a part of them. In the same zone 

 are Quercus fulvescens, Quercus densifiora, and Quercus Kelloggi, which do not, however, occur 

 in any considerable numbers. 



LOCAL BOTANY. 



In crossing the Sierra Nevada, over the base of Lassen's butte, for twenty miles our route, 

 gradually ascending, led among grooves of the three species of oak which I have mentioned as 

 prevailing about Fort Reading, with scattered trees of the nut pine, the greater part of the 



