10 BULLETIN 460, U. S. DEPARTMENT OF AGRICULTURE. __ J 
a Scotch botanist, published the first account of the tree in 1853 under 
the name Pinus flexilis, confusing it with the limber pine, which 
was discovered and named 20-years before. Likewise, in 1857, Dr. 
Newberry erroneously referred to it as Pinus cembroides. It re- 
mained for Dr. George Engelmann to describe this pine technically 
and to establish its present name, Pinus albicaulis, in 1863. The 
French botanist Carriére named it Pinus shasta in 1867, while as 
late as 1880 Dr. Engelmann, then concluding that it was a closely 
related form of the hmber pine, renamed it Pinus flewilis var. albicau- 
lis. As now known, however, the white-bark pine is specifically dis- 
tinct from our other white pines." 
DISTINGUISHING CHARACTERISTICS. 
White-bark pine has a low, long-branched, twisted, or crooked 
trunk from 15 to 50 feet high and from 10 to 24 inches in diameter. 
Taller and larger trees occur in protected situations. In the higher 
wind-swept places it is often reduced to a sprawling shrub with enor- 
mous branches spreading over the ground. Young trees have distant, 
regular whorls of branches which stand out at right angles to the 
trunk, but in later life some of the upper whorls of branches develop 
upward into long, willowy stems, giving the tree a loose, bushy 
crown. The branches, especially near the trunk, are exceedingly 
tough and flexible, so that the tree is able to withstand the fiercest 
storms without being broken. : ; 
The bark, even of old trees, is little broken, except near the base of 
the trunk, where it is rarely more than one-half of aninchthick. Here 
narrow cracks divide the bark into very thin whitish or brownish 
scales, which when torn off reveal the characteristic red-brown inner 
bark. Elsewhere the bark is rarely more than one-fourth of an inch 
thick. Twigs of a year’s and sometimes of two years’ growth are 
slightly downy. 
The dark yellow-green leaves (Pl. VI), densely clustered at the 
ends of the branches, are borne in bundles of 5, and are from about 
14 to 22 inches long. Shorter leaves occur on trees in the most ex- 
posed situations (Pl. VI, d). The margins of the leaves are com- 
monly smooth, but sometimes they have very widely separated minute 
teeth. A cross section of the leaf shows two resin ducts (centrally 
located on the dorsal or back side of leaf) ; occasionally a third resin 
duct occurs on one of the lower sides. The leaves of each season’s 
1 White-bark pine was probably first introduced into cultivation in Scotland through the 
seeds John Jeffrey is said to have sent there from Mount Shasta, California, in 1852 (fide 
Elwes and Henry, op. cit., 1049). Elwes and Henry state that no plants appear to have 
survived, and that the only specimens now known (1910) are seedlings growing in Kew 
Gardens. It is probable that, like the limber pine of similar habitat, the white-bark pine 
can not be successfully grown in eastern United States. However, it is in no way at- 
tractive as an ornamental tree. 
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