40 BULLETIN 460, U. S. DEPARTMENT OF AGRICULTURE: 
DISTINGUISHING CHARACTERISTICS. 
In the Pacific slope region this pine grows in rather open stands 
and forms a dense rounded or pyramidal crown of large, much- 
forked branches which often extend down to the ground. In its 
high mountain range within the Rocky Mountain region it grows in 
very close stands and develops a tall, clean, slender shaft with a 
short, rounded, small-branched crown. This characteristic form in ~ 
its more eastern range has given the tree the name of “lodgepole 
pine.” The thin scaly trunk bark is pale brown with a grayish tinge. 
In close stands the height is from 50 to 100 feet, the usual diameter 
being from 12 to 24 inches. Taller and larger trees sometimes occur. 
The smooth looking trunks are clear of branches for from 30 to 60 
feet. 
The foliage is a bright yellow-green. The leaves (Pls. X XVI, 
X XVII) are borne in bundles of 2 and are nearly one-eighth of an 
inch wide and from about 1 inch to nearly 3 inches long, but usually 
they are about 2 inches long. Each season’s growth of leaves remains 
on the trees for from 6 to 8 years. Young trees, however, sometimes 
retain their leaves for 9 years. The edges of the leaves bear minute 
sharp teeth (serratures). A cross section of the leaves shows one 
or two resin ducts. 
The cones (Pls. XXVI, X XVII) ripen late in August and Sep- 
tember of the second season. On many trees, the cones open in late 
autumn and shed nearly all of their seeds, while the cones of other 
trees in the same locality may remain closed for a number of years. 
The cones adhere to the branches for a great many years, some of 
the closed ones finally opening and liberating their seed.t_ When the 
cones are fully ripe the tips of their scales are shiny and of a clay- 
brown color, the inner or unexposed portion being a bright purple- 
brown. The seeds (Pl. X XVII, 6) are a deep reddish-brown, with 
black-brown spots. The seed-leaves vary in number from 3 to 6, but 
usually there are 5 (Pl. X XVII, a). 
The wood of trees grown in dense stands, as in the Rockies, is ex- 
tremely narrow-ringed; while that of trees in open forests, as in the 
Pacific region, is moderately wide-ringed. The thick layer of sap- 
wood is almost white and the heartwood is of a clear yellow or 
yellowish-brown color; the heartwood of the Pacific coast form is 
usually pale brown tinged with red. The wood is rather hard, stiff, 
and straight-grained. A cubic foot of the dry wood of the Pacific 
1The wonderful reproductive power of this species on areas over which it has been 
killed by fire is dependent upon the ability of the closed cones to endure a fire which 
kills the trees without injuring their seeds. After fire, the cones open, shed their seeds 
on the bared ground, and a new growth springs up. Another remarkable adaptation in- 
suring this tree against extinction by fire is its habit of producing fertile cones at the 
early age of from 7 to 10 years. 
