FOREST TREES OF THE PACIFIC SLOPE. 285 



to Marin County, and south of San Francisco to Santa Cruz Mountains. Locally noted 

 on most south slopes and valleys of Trinity National Forest, such as Grouse Creek, on 

 Humboldt Trail, near South Fork Mountain, at 2,500 feet, Rattlesnake Basin, at 3,800 

 feet, and creek bottom near Friends Ranch, at 3,700. 



OCCURRENCE. 



In alluvial high bottoms, valleys, prairies; less commonly on dry hill and (north) 

 mountain slopes. In deep, fresh, humous soils (largest in west Washington and Oregon), 

 and also in dry, gravelly or rocky soils (small or scrubby). Occurs only in open mixture; 

 usually with Kellogg oak and Douglas fir, but also with madrofia, western yellow pine, 

 and Oregon ash. 



Climatic Conditions. — Similar to those of Douglas fir. 



Tolerance. — Endures slight shade in youth. 



Reproduction. — Prolific periodic seeder (about every two years). Seedlings rather 

 scarce, most frequent on moist humous soil and litter ; unbroken, grassy surfaces where 

 seed trees often grow are unfavorable for reproduction. 



Sadler Oak. 

 Querent sadleriana R. Brown Campst. 



DISTINGUISHING CHARACTERISTICS. 



Sadler oak — named in honor of a Scottish botanist — has no common name ex- 

 cept " scrub oak." Though it is only a shrub under 6 feet in height, it is included 

 here because of its value as a slope cover. It produces extensive dense thickets 

 on high, dry slopes between about 4,000 and 9,000 feet elevation. The very dis- 

 tinct form of its loaves (fig. 120), which are thick, deep yellow-green, smooth, 

 and shiny on their upper surfaces, and white, smooth, or slightly hairy beneath, 

 readily distinguish it from any other associated oaks. The leaves, though not 

 strictly evergreen, remain on the branches until the next season's foliage is 

 produced. Acorns are matured in one season. 



RANGE. 



Coast and Siskiyou mountains of southwestern Oregon and northwestern California. 

 Oregon. — On top of coast mountains along old Wimer road; top of Siskiyous near 

 Happy Camp Trail. 



California. — Crescent City Trail, Del Norte County, near Oregon line. 



OCCURRENCE. 



Mountain slopes in dry, rocky and gravelly soil. In extensive thickets of pur.- growth. 



Blue Oak. 

 Quercus douglasii Hooker and Arnott. 

 DISTINGUISHING CHARACTERISTICS. 



Appropriately called blue oak on account of the blue-green color of its foliage, 

 but known locally also as "white oak." from its light, ashy-gray bark. Trunks 

 exposed to the sun are especially light colored, sometimes even whitish, but are 

 considerably darker gray in sheltered situations. 



Usually small or medium sized, from. 30 to 40 feet high and from 10 to 15 



inches in diameter: exceptionally, from 60 to 75 feet in height and 2 feet in 



diameter: larger trees occur, but very rarely. The rather t li in. narrowly ridged 



bark flakes off easily. The smooth-looking trunks are short and clear of branches 



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