180 



THE AMERICAN NATURALIST 



[Vol. XLVI 



Passing southward from Oregon into California, the outer 

 coast mountains from the Oregon line to Santa Cruz, some fifty 

 miles south of San Francisco, are dominated by the Redwood (Se- 

 quoia sempercin us), the tallest of all trees, which reaches its 

 greatest development in the northern coast counties of Mendocino 

 and Humboldt. These giant trees occur only in the narrow belt 

 within reach of the heavy summer fogs which prevail along the 

 coast. In most parts of the Redwood belt there is a greater or 

 less mixture of other trees, e. g., Madrono (Arbutus 3Ie>,ziesii) , 

 the Tan bark Oak (Que reus elensiflora) the Douglas Fir, wild 

 Nutmeg (Tor re yet calif arnica) , the wild Bay tree (Umbellularia) 

 and the big-leaved Maple. 



South of San Francisco there is a rapid diminution in the rain- 

 fall and the Redwoods gradually . disappear and are replaced 

 by more xerophytic types. Some of these, like the Monterey-Pine 

 and Cypress and the Torrey Pine of Southern California, are of 

 very restricted range, forming scattered forests along the coast, 

 and extending down to the very edge of the ocean. 



Many of the plants of the Redwood belt are northern types 

 which thrive in the cool forests of the outer coast range. Repre- 

 senting familiar northern and southern genera may be men- 

 tioned species of violets, Trillium, Clintonia, Oxalis, Smilacina, 

 Asarum, Aquilegia, Delphinium. 



Of characteristic shrubs of this region there may be cited spe- 

 cies of Ribes, Ceanothus, Gaultheria, Rhododendron, Azalea, 

 Vaecinium, Rubus and Arctostaphylos. In middle California 

 these northern plants follow the shady canons almost to the 

 level of the valleys, where they mingle more or less with the 

 valley flora which is comprised mostly of strictly Western types. 



In many places along the Coast there is an extensive devel- 

 opment of sand dunes, which support a very rich and interesting 

 flora. Characteristic plants of the sand dunes are species of 

 Abronia, Lupinus, Erigeron, CEnothera, Eschscholtzia, Fragaria, 

 Mesei 1 1 1 ova nthemum. 



In middle California three ranges of mountains parallel with 

 the coast are found. The Outer Coast-range skirts the ocean, 

 and a break in this at San Francisco forms the Golden Gate, 

 opening into the Bay of San Francisco, which receives the united 

 waters of the two rivers draining the great central valley. The 

 latter is separated from several smaller valleys to the west, the 

 most important being the Santa Clara Valley, by the inner Coast 



