30 



EVERGREENS OF COLORADO 



II. Needles (leaves) of vigorous lower branches one and three-fourths 

 to three inches long. The two resin tubes close to the lower sur- 

 face. Cones green, yellow or purple. 



2- Abies concolor. 



Fig. 19. Blue Spruce, a. Stalk-like bases on twig after needles 

 have fallen, x2. b. Twig with needles attached, x2. c. Cross-section of 

 needle, xlO. 



