EVERGREENS OF COLORADO 



31 



1. BALSAM FIR, ALPINE FIR. 

 Abies lasiocarpa. Nutt. 



This tree, which occurs throughout the mountainous parts of west- 

 ern North America, in Colorado frequents the high mountain slopes and 

 summits and appears to some extent along the streams which flow 

 through the mountain parks. While it may occasionally be found as low 

 down as 9,000 feet, it is most common between 10,000 and 11,000 feet 

 and from there in scattered growth 

 to timber-line. It is a common ad- 

 mixture with Bngelmann spruce 

 and forms one of the weed trees in 

 Engelmann forests. In Colorado 

 it is a medium sized tree, seldom 

 over 100 feet tall and one to two 

 feet in diameter. In shape, it is 

 narrowly conical and occasional 

 specimens are found which are 

 nearly perfect in form. 



The needles on the lower 

 branches and on young trees are 

 usually blunt or sometimes slightly 

 notched at the tip, while on fruit- 

 ing branches they are short, pointed 

 and curved upward. They often 

 possess a whitish or silvery bloom 

 much like that of the blue spruce. 

 When cut across, each needle shows 

 two minute ducts or tubes full of 

 resinous juice, situated about mid- 

 way between the upper and lower 

 surfaces near the margins of the 

 needle. While these tubes can be 

 distinguished with the naked eye, 

 it is necessary to examine them 

 with a hand lens in order to note 

 their position with any degree of 

 accuracy. It is often sufficient to 

 break the leaf across in order to 

 bring them to view. 



The trunks of young trees retain 

 the old needle scars for many years 

 on account of the smooth bark. 

 The resin blisters are numerous and 

 appear like slight scattered swell- 

 ings just under the outer baric and when cut into, the pitch or resinous 

 juice which they contain readily oozes out. 



Fig. 20. 



Eng-elmann Spruce, grow- 

 ing in the open. 



