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20 BULLETIN 460, U. S. DEPARTMENT OF AGRICULTURE. 
The foliage of adult trees is a dark yellowish green, while that of 
seedlings is a bright bluish green. Each season’s growth of leaves © 
remains on the branches for nearly 9 years, though a good many © 
leaves fall during the fourth summer. The leaves are borne in clus-— 
ters of 2, occasionally of 8 (Pls. XI, XII). They are sharp pointed, 
often curved, and vary in length from about seven-eighths of an inch 
to nearly 12 inches. The margins of the leaves are smooth (without — 
minute teeth). In cross section the leaves show two resin ducts. 
The yellowish-brown and somewhat shiny cones (Pl. XI) are from — 
about 14 to nearly 1? inches long. They ripen in August and Sep-— 
tember and shed their nutlike edible seeds (Pl. XI, 6) during the 
latter part of September and in October, the very short rudimentary 
wings (from one-eighth to one-sixth of an inch long) remaining at- 
tached to the cone scales (Pl. XI, a) when the.seeds fall. Unexposed 
parts of the cone scales are pale red-brown. The perfect seeds,t borne @ 
only by scales in the middle of the cone, are pale yellow with reddish- 9 
brown specks and mottlings on one side and dull red-brown on the 
other. Most of the empty cones fall from the trees during the first @ 
winter or early the following spring. The seed-leaves (Pl. XII, a,b) 
vary in number from 7 to 10. | 
The wood of Pinus edulis is narrow-ringed and hard, but very 9 
brittle. The thin layer of sapwood is nearly white, and the heart- @ 
wood is ight yellowish brown. Next to that of Pinus cembroides it 
is the heaviest of Rocky Mountain pine woods, a cubic foot of dry 
wood weighing nearly 40 pounds. It is used largely for fuel, ties, % 
fence posts, and other local purposes. 
OCCURRENCE AND HABITS. 4 
Pinus edulis grows on dry foothills, mesas, mountain slopes, and 
sides of canyons, at elevations between 5,000 and 9,000 feet, or occa- 9 
sionally somewhat below 5,000 feet (Map No.6). It is usually found ¥ 
in poor, rocky, gravelly soils, but often in shallow or deep layers of 
gravel and sand overlying rock, and sometimes in the crevices of 
rocks. Very commonly, it is associated with western yellow pine, © 
one-seed juniper, Utah juniper, mountain mahoganies, Gambel oak, 
and mountain red cedar. Its most frequent associates are, however, 7 | 
the one-seed and Utah junipers. Occasionally it forms pure stands of 7 | 
limited extent. The largest growths occur on mesas and elsewhere 7 
at the lower elevations noted, where the sandy or gravelly soil 
deposited by washing is moderately rich. 
Pifion is very intolerant of shade in all but the seedling stages of 
its growth, a period when partial shade assists the young plants to 
1Jndians and settlers gather large quantities of the seeds; the former use them largely \ 
for food, and the latter send them to eastern and other city markets as sweetmeats.” 
Birds and squirrels and other rodents, however, claim a large share of pion seeds, many — 
of which are devoured before the cones open, 
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