Olympie Distriet. — Californian Region. 603 
while the height of the snow-capped mountains permits a boreal flora to exist 
in a region otherwise inimic to such plants; the interior valley of California 
also bears a unique vegetation and the coast range flora is quite distinct from 
that of any of the nearby phytogeographic districts. As a whole: this part 
of the Pacific Section makes an interesting transition between the northern 
wooded and the southern arid territories. 
A. Coast Range District. 
This extends along the Coast of the Pacific Ocean from Rogue River and 
the Siskiyou Mountains (42° N. latitude) south to the latitude of Point Con- 
cepcion (34° 30’). Its continuity is broken in the neighborhood of San Fran- 
cisco Bay, where the interior valley is entered by tidal sea water. We can, 
therefore, distinguish a northern (Mendocino) area and a southern (Santa Lucia) 
area. As we have made evident (see ante pages 271—275), the flora of the 
Coast ranges is interesting in possessing many elements. The true Coast 
range flora is endemic and much the oldest and most unique. It also lacks 
the northern genera which may be called boreal-alpine. The northern element 
from Oregon and Washington is practically co@xtensive with the redwood area; 
the herbaceous undergrowth in the redwood area being northern. The 5o- 
noran element overlaps the southern portion of the Coast Range between 
San Francisco Bay and Tehachapi Pass. Such a flora merits more than a 
passing notice. 
a) Mendocino Area. 
The Coast Range to the north of the Bay of San Francisco is a peculiarly 
dislocated complex of mountains. Nothwithstanding its heavy annual rainfall, 
the area has a period of drought from about the end of July until about 
the end of September, but during this period, according to the observations 
of the writer at Humboldt Bay, the forest is by no means dry, because dense 
fogs roll in from the Pacific and precipitate considerable moisture‘). The limits 
of the sea fogs are just about the limits of Seguoia and the higher ridges in 
consequence above the fog level support only a scattering growth of redwood. 
In general, the distribution of the tree growth of the northern Coast Moun- 
(a) Immediately along the coast shore, and outside the redwoods, brush 
growths and a growth of coniferous trees of various kinds. 
(b) The redwood strip, occupying the western slope of the outer backbone 
of the Coast Range. 
(c) Following the redwoods, a separate development of trees, which are 
found in the redwood strip in conjunction with the redwood; strip of Pseudo- 
tsuga Douglasii, Quercus (Pasania) densifiora, Castanopsis chrysophylla etc. 
I) See also Cannon, W. A.: On the Relation of Redwoods and Fog to the general Precipi- 
tation in the redwood Belt of California. Torreya, I: 137. 
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