12 BOTANY. 



below. This is the northern limit of the red-wood. Thence northward, it is succeeded by the 

 western white cedar, Thuja gigantea — Douglas' & Menzies' spruces; and these form the dense 

 and almost impenetrable coating of vegetation which covers the coast mountains from Port 

 Orford to the Columbia — Douglas' spruce here attaining its greatest dimensions, fully equalling 

 those of the red-wood and sugar pine. 



In the valleys of the Umpqua and other rivers, which discharge themselves into the ocean, 

 Quercus garryana grows in groups and as solitary trees, in the open grounds. It attains a 

 diameter of from 2 to 3 feet, and assumes the low and spreading form common to the oaks of 

 the valleys of California and Oregon. 



The undergrowth of the coast mountains is composed of so large a number of plants as to 

 forbid their enumeration. Near San Francisco the shrubby undergrowth is made up, in a 

 great degree, of the " wild lilac," (Ceanothus thyrsiflorus,) Ceanothus rigidus, and the bush 

 lupine, (Lupinus macrocarpus.) About Port Orford, and thence northward, the " salmon 

 berry" (Rubus spectabilis) is a conspicuous feature in the vegetation. It here grows to the 

 height, sometimes, of six or eight feet, and bears a profusion of fruit, which is very attractive 

 in appearance, and sometimes of excellent flavor. Thickets of Rhododendron maximum are of 

 common occurrence, and by their stiff and tangled branches frequently form a serious obstacle 

 to the progress of the traveller. Towards the Columbia, thickets, similar in appearance and 

 character, are formed by Ceanothus velutinus. In the spruce forest, where not so dense as to ex- 

 clude all undergrowth, the ground is covered with a carpet of the " salal" (Gaultheria shallon) 

 and the Oregon grape, (Berberis pinnata.*) Ferns and mosses grow in great abundance in some 

 localities, furnishing very good indices of the moisture of the climate. Among the ferns, Aspi- 

 dium munitum is the handsomest, Pteris aquilina the most abundant. Where the forest has 

 been burned off, this last mentioned fern takes exclusive possession of the surface, and grows so 

 dense and tall as to make the passage through it painful, even for one on horseback. In the 

 transverse chains of mountains which run back from the coast to Mount Pitt and Mount Shasta, 

 Pinus Lambertiana, Pinus ponderosa and contorta, Picea grandis, and, perhaps Picea amabilis, 

 reach down nearly to the seashore. 



SACRAMENTO VALLEY. 



The geological structure of the Sacramento valley, with the characteristics of its soil, are 

 given at some length in the second chapter of the accompanying geological report. 



Climate. — The climate of the Sacramento valley affords a marked contrast to that of the coast. 

 While the temperature in winter is never so low but that the grass is constantly green, and 

 flowers, in the southern portions, perpetually in bloom, in summer the heat is intense to a de- 

 gree never experienced in any portion of the eastern States. 



The rain-bearing winds from the ocean during this season are either entirely excluded by the 

 wall which bounds the valley on the west, or pass over to the Sierra Nevada, depositing none of 

 their moisture. From May to November rain almost never falls, and neither clouds nor mist 

 are seen during the greater part of that time. The effect of the sun's rays, beating down with- 

 out obstruction into this enclosed area, is to elevate the temperature of the air frequently to 

 112° — 115° Fah. in the shade, and to dry up and parch the surface to such an extent that the 

 growth of annual plants is arrested as completely as by the snows and frosts of the winter of the 

 northern Atlantic States. With the return of the autumnal rainy season vegetative life is 



