Coast Range District. 611 
e chaparral formation ceonsists of ee, fasciculatum, Ceanothus cuneatus, associated 
with a chrysolepis, Q. Wislizeni, Q. Douglasii and Pinus sabiniana. The vegetation of this 
mountain also comprises: Rhamnus ilicifolia wei rounded clumps near the summit), Ribes 
a (at the summit), R. californieum (near the summit), Clematis lasiantha (cli imbing over 
e summit), Aplopappus (Stenotus) linearifolius, a shrub of the south slope, while 
eek hispidus (endemic), Phacelia Breweri, Silene verecunda, Psoralea californica, Sanicula 
saxatilis, Helianthella castanea (endemic), Hosackia crassifolia, Campanula exigua, Arabis Breweri, 
Lathyrus vestitus and Collinsia tinctoria occupy rocky situations on the top of the mountain. 
open spaces among the bushes are occupied by Eschscholtzia ambigua, Delphinium californicum, 
Armnica discoidea, Campanula exigua and Phacelia circinatiformis. Arabis Breweri, Erigeron folio- 
sus grow on south slopes while Pentstemon corymbosus forms mats on the exposed rocks. 
The vegetation of Mount Hamilton shows a marked xerophytic cha- 
racter as compared with that on Mount Diablo and Mount St. Helena. The 
absence of a true forest is noteworthy and the coast range oaks Ouercus 
dumosa, Q. Wislizeni, O. agrifolia, O. californica (= O. Kelloggii) occur more 
generally on the north slopes with Ouercus Douglasii on the western flanks. 
Pinus ponderosa grows on the summits of high ridges, while Pinus Sabiniana 
occurs on the highest parts of the mountain. Species of Ceanothus are absent. 
Other trees of the mountain are Cercocarpus parvifolius (= C. betulaefolius), Acer macro- 
phyllum, Aesculus californica and Rhus diversiloba. The north slopes show the presence of 
Hosackia crassifolia, Eriogonum saxatile, Umbellularia californica en gulches almost to the summit), 
Erigeron petrophilus (crevices of rock) and Pentstemon brevifloru 
South slopes are occupied by Eriogonum stellatum, E. ee Oenothera hirtella and 
Chlorogalum pomeridianum, while Holodiscus discolor is common along rocks and thickets on 
the highest ridges. Lewisia rediviva (see Fig. 22 page 338) also occurs on Mt. Diablo and in the 
Rocky Mountains of the northwest. Arenaria (Moehringia) macrophylla is plentiful on rocky slopes. 
Abies venusta is a tree confined to the Santa Lucia Mountains and neighboring hen 
and canyons. It oceurs at least eighteen miles inland from the ocean on crags, rocky ridges, 
eanyons and along streams. In favorable localities where the chaparral does not occur it 
mingles with Pinus ponderosa, Pinus Coulteri to form considerable tracts into which Quercus 
chrysolepis, Q. californica (= Q. Kelloggii), Q. (Pasania) densiflora, Pinus attenuata, and Arbutus 
Menziesii extend. Elsewhere these mountains which rise to elevations of 4,500 to 5,000 feet are 
largely covered covered with chaparral ?). 
B. San Joaquin District. 
The central valley of California, situated between the Sierra Nevada Moun- 
tains on the east and the Coast ranges on the west, is drained by the Sacra- 
mento River running from the north toward the south to join the San 
Joaquin River which flows from the south toward the north. The stream 
formed by their confluence empties into San Francisco Bay. The topography 
and geologic history of this great valley situated almost at Sea level has been 
previously described (see ante p. 279). It remains to discuss the plant forma- 
tions of this interesting plain. 
1) Duprey, WırLıam R.: A notable California Fir. Forestry and Irrigation, VIII May 1902: 193; 
PEIRCE, GEORGE J.: Botanical Aspects of Stanford University. The Plant World ı2: 245-252 
Nov. 1909. . - 
39* 
