14 The: Coi^orado Expe:rime:nt Station. 
GENUS PinUS -THE PINES. 
The pines form the most important group of the cone-bearing 
trees. As indicated in the key they are most easily recognized by 
the needles being in bundles of two or more with a short sheath 
at the base. This sheath, together with the needles which it sur¬ 
rounds at the base, grows from a very short twig which arises 
just above a small, brownish scale that also represents a form of 
leaf. The staminate flowers occur in small cone-like clusters 
crowded around the stems at the base of the new growth of the 
season. After the blossoming, which occurs quite early in the 
growing season of the tree, the staminate flower clusters dry up 
and fall off and thus leave a bare space on the branch which bore 
them. The pistillate or seed-bearing cones appear near the tips or 
along the sides of the new growth. At first they are small and 
are usually overlooked. After the blossoming period they develop 
rather slowly and do not mature their seeds until the second 
autumn. The scales of the cone are thick and hard and in some 
species each is furnished with a sharp curved prickle. Two seeds 
are borne at the base of each scale. As the seed matures a part 
of the scale peels off wtih the seed and forms its wing. 
KEY TO THE COLORADO SPECIES OE PINUS. 
I. Needles, five in a bundle. 
a. Scales of the cone tipped with curved prickles. 
1. Pinus aristata. 
b. Scales of the cone without prickles. 
2. Pinus fiexilis. 
II. Needles two to three in a bundle. 
A. Needles 8-12.5 c. m. (3-5 in.) long. 
3. Pimis scopulorum. 
B. Needles not over 6 c. m. (2% in.) long. 
a. Needles 3-6 c. m. (lVi-2% in.) long; seeds small, 4-5 m m. 
(5/16 dn.) long. 
4. Pinus Murrayana. 
b. Needles 2-4 c. m. in.) long; seeds large, 10-15 m m. 
(%-% in.) long. 
5. Pinus eduliSy 
EOXTAIE PINE, HICKORY PINE. 
{Pinus aristata, Engelm.) 
(Plate II B) 
The foxtail pine occurs chiefly in the higher altitudes among 
the mountains of central and southern Colorado, in Utah, Nevada 
and southern California and Arizona. It is a small or medium 
sized tree of bushy habit, seldom reaching a height of I2-I5m. 
^i'he short needles grow in bundles of five closely crowded along 
