a BULLETIN 460, U. S. DEPARTMENT OF AGRICULTURE. | 
and those produced each year remain on the branches until about the 
third summer ; in some instances, however, many of them die and fall 
from the trees during the second season. They are usually curved, 
and are borne in bundles of two (Pl. XXVIII, a, 5). In length they 
vary from about seven-eighths of an inch to nearly 14 inches, but 
commonly they are about an inch long. The edges of the leaves bear 
minute and widely-separated teeth (serratures). A slightly mag- 
nified cross section of the leaf shows, as a rule, two resin ducts, 
one in each angle of the section (edge of leaf) ; occasional leaves ap- 
pear to be without resin ducts. 
The characteristically one-sided cones (Pl. XXVIII, 5, c) are 
fully mature by September of the second season, and two, three, or 
four of them may be borne in one cluster. They vary in length 
from 14 to about 2 inches and from one-half to nearly 1 inch in 
diameter at the thickest place. Early in autumn they are a greenish 
to a deep purple, but later they turn to a hight clay-brown, the ends 
of the closely pressed cone scales being shiny. During the first season 
the scales of young cones bear delicate curved prickles, which, how- 
ever, usually disappear or are very inconspicuous by the time the 
cones are ripe. <A characteristic habit of the cones of this pine is to 
remain attached to the trees for from 12 to 25 years or more. The — 
cones are peculiar also in that they open irregularly and liberate 
only a few of their seeds at a time and then usually only after the 
cones have remained closed for two or three years. The triangular 
seeds are from one-eighth to three-sixteenths of an inch long and — 
about three thirty-seconds of an inch wide, and are covered with a — 
blackish-brown minutely pebbled membrane, tiny bits of which — 
become detached and show the hght yellow-brown shell of the seed © 
beneath. The upper side of the seed is more or less distinctly marked 
with two grooves. The seed-leaves vary in number from four to 
five (Pl. XXVIII, e; lowermost long leaves). 
Jack pine wood is variable in texture and weight from rather soft 
and light to rather hard and moderately heavy, some grades of the 
wood being nearly of the same hardness and weight as Norway pine. | 
A cubic foot of dry wood weighs about 292 pounds. When seasoned — 
a 
7 
it is brittle and weak and decays rapidly in contact with earth. The 
sapwood is thick and of a uniform pale creamy white, but the heart- 
wood varies in color from a bright, slightly brownish yellow to a 
light yellow-brown. The wood formed during the first 15 or 20 
years, when the tree grows rapidly, is moderately wide-ringed; that 
formed during the remainder of the tree’s life, when diameter growth 
is very much slower, is narrow-ringed—sometimes exceedingly so. 
Little is known now regarding the use, if any, of this timber in the 
far northwestern range of the tree. In the central and eastern parts 
