FOEEST TREES OF THE PACIFIC SLOPE. 35 



Never forms dense pure stands. Most abundant in chaparral on east slopes with single- 

 leaf pinon, oaks, and juniper, and in thinner stands on w<-st and south slopes in dense 

 chaparral. Number of trees varies per acre from 5 to about 100. In Lower California, 

 in open forests, often with single-leaf pinon pine. Throughout its range, heaviest' growth 

 is at higher altitudes than that of pinon. 



Climatic CONDITIONS. — Best growth requires moister climate, without such extremes 

 of temperature as are endured by single-leaf pinon. Seasonal temperature of its ran-.' 

 between 15° and 100° F. Rainfall averages between 15 and 25 inches throughout its 

 distribution. 



Toleuance. — Little known of light requirements, but its growth in dense chaparral 

 indicates tolerance of shade during early youth. 



Reproduction. — Moderate seeder; cones often locally produced about every year. 

 Wingless seeds, shed near tree, are largely eaten by birds and squirrels and gathered 

 by Indians for food. Exposed soil with little humus most favorable seed-bed. Germina- 

 tion moderate. 



Single-leaf Pine. 

 Finns monophylla Torrey and Fremont 



DISTINGUISHING CH UtACTERISTIGS. 



Unique among all American species in having single leaves, as indicated by 

 its scientific name. Generally known as " nut " or " pinon " pine, hut it is 

 highly desirable that the distinctive mark of this tree should he fixed by adopt- 

 ing " single-leaf pine *' as its common name. Mature trees have short trunks, 

 rarely straight, and wide, rather flat crowns of short, heavy, twisted, and bent 

 branches, which are given off near the ground and often hang low, giving the 

 appearance of an old apple tree. Young trees, with their low. thick trunks, sur- 

 mounted by pyramidal crowns of rather straight, rising branches, have a very 

 different aspect As a rule, the single-leaf pine does not exceed 25 feet in beighl 

 and from 12 to 15 inches in diameter. In protected and otherwise favorable 

 situations it may reach a height of from 35 to 50 feet, but it is characteristically 

 a low. sprawling tree. Bark of young trunks is smooth and dull gray, 

 while that of old trunks is roughly and irregularly furrowed, nearly an inch 

 thick, and with thin, close, dark brown, sometimes reddish brown, scales. The 

 general color of the foliage is pale yellow-green with a whitish tinge The 

 Single (or very occasionally double) leaves are stiff, curved toward the branch. 

 prickly, and from about 1J to 2$ inches long — generally about U inches long 

 (fig. 9). A season's growth of leaves remains on the tree about five years; not 

 rarely leaves persist ten to twelve years. A striking peculiarity of seedling 

 trees is that they continue to produce only primary leaves for six or seven 

 years, after which they put forth normal foliage. Cones (fig. 9) are matured 

 in August of the second season: they shed their s,.,m1s. which leave their thin. 

 narrow wings attached to the cone scales, within about a month afterward, 

 when the tips of the scales become shiny and a deep russet-brown. Most of 

 the empty cones fall from the trees during the winter or spring. The seeds 

 (tig. 9, c), are dark chocolate brown, with dull yellowish areas; extensively 



gathered by Indians for food. S 1 leaves. 7 to 1". Wood, yellowish brown. 



very fine-grained, moderately light, and very brittle. 



Longevity. — An exceedingly slow-growing tree, reaching an age of from 100 to 

 225 years. Further records of longevity are required. 



RANGE. 



Desert regions of Utah, Nevada, Arizona, southeastern California, and northern Lower 

 California. 



California. — In southern Sierras, on east slopes at about 6,000 to 8, I feel from 



Loyalton, Sierra county (extreme northern limit probably still undetermined) and 



Markleeville Creek (east side of Sierras) southward to vicinity of Walker Pass, where 



