Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean: Vol. 6, Pt. 3

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," (Ceanot1hus t7tyrsiforu8,) Ceanothus rigidus, and the bush
lupine, (Lupinus macrocarpus.) About Port Orford, and thence northward, the "salmon
berry" (lRubus 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 exclude 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, Aspidium 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 amaTilis,
reach down nearlv 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.
CGlrnate.-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 degree 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 without obstruction into this enclosed area is to elevate the temperature of the air frequently to
112o115h Fah. in the shade, andt 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
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