38 MISC. PUBLICATION 18, U. S. DEPT. OF AGRICULTURE 



inches in diameter. In spite of having only 60 to 90 days growing 

 season, Engelmann spruce grows faster than any other species. 

 Trees 500 years old are not uncommon. 



Throughout the world the true firs are companions of the spruces 

 and are often called "balsams." Alpine fir (Abies lasiocarpa) will 

 be readily distinguished from spruce by its nearly white smooth 

 bark, becoming furrowed (never scaly) only when the stem ap- 

 proaches a foot in diameter. The leaves also instead of being square 

 and pointed are flat and blunt. They tend to turn upward on twigs, 

 so that it appears as though none were attached to the lower sides 

 of the twigs. If one looks at the end of any twig of a true fir, except 

 when the twigs are growing rapidly in the early spring, he will 

 always find there three blunt, shiny, resin-coated buds. 



The white fir (Abies coneolor), locally known as silver fir, is much 

 like the alpine fir, except that its foliage is a pale pea green and the 

 needles often 2 inches or more long. It grows at the lower elevations, 

 on hillsides, with western yellow pine and Douglas fir, and in the 

 canyons with blue spruces. Its association with pine and Douglas fir 

 violates all the rules of conduct for well-behaved true firs. The light 

 color of the foliage makes the white fir a beautiful tree, and besides 

 this it usually bears on the uppermost twigs a cluster of large, erect 

 cones, pale green on some trees but more often a deep rich purple. 

 "When the cones of a fir ripen the scales fall off, leaving the stalks or 

 cores of the cones still standing upright and strongly suggestive of 

 Christmas candles in the tops of the trees. 



Lastly comes the Douglas fir (Pseudotsuga taxifoHa), which is 

 neither fir nor spruce, but possibly a close relation of the hemlocks. 

 Douglas fir is one of the most widespread trees in the Pikes Peak 

 region, and there is evidence that it formerly composed vast and 

 splendid forests in many parts of Colorado and Wyoming, but that 

 these forests have been almost exterminated by fires of b}^-gone cen- 

 turies. In many cases lodge-pole pine has taken the place of Douglas 

 fir, but remnants of the fir forests are often found. Douglas fir in 

 the Rocky Mountains, while inferior to its western brother, which 

 reaches such magnificent proportions on the Pacific coast, is never- 

 theless one of our most valuable trees, its wood being very durable 

 and highly prized for railroad ties and posts. 



There are two features of Douglas fir which make it readily dis- 

 tinguishable from all other conifers. At the end of a twig one will 

 always find a single 4 cone-shaped, sharp-pointed bud, brownish red 

 in color. On the branches, after the tree is 8 or 10 feet tall, one may 

 almost always find dry cones which are light and papery in texture. 

 Between the smooth, round scales of these cones there project nar- 

 rower, papery bracts, three-pronged at the tips. No other cones have 

 this feature, which appears to be purely ornamental. When the 

 cones are young (say, until July) the cones themselves are purple, 

 while the three-pronged bracts are green, creating a colorful con- 

 trast, Douglas fir occurs generally at middle elevations (8,000 to 

 9,000 feet) but also at low elevations on cool, northerly aspects. 



4 Only rarely is there more than one bud. 



U.S. GOVERNMENT PRINTING OFFICE : i928 



