THE SILVA OF COLORADO 



257 



which refers the user of the key to the next line which is to be 

 consulted. This may give at once the desired name or it may 

 refer to a still lower line. At any rate the process is to be continued 

 until the name of the genus is found. Noting the number of the 

 genus, as well as the name, the student should now turn to the proper 

 place in the following pages and, with the aid of the special key, deter- 

 mine the exact species. Both the scientific and English names are given 

 since both are likely to be useful to one interested in botany or forestry. 



Key I. For Identification of Colorado Evergreens 

 1 a. Trees with needle-like foliage leaves; fruit a cone. (2) 



lb. Trees with scale-like, overlapping leaves, fruit a small berry (cedars). 



Genus 5. Sabina 



2a. Foliage leaves (needles) in bundles of two or more surrounded at base by a short 



sheath. Leaves mostly more than 25 mm. (1 in.) long. Cones hard and woody 



when mature. Genus 2. Pinus 



Fig. 2. — Leaves of Coniferous Trees. 

 (Pseudotsuga); 3. Spruce (Picea); 4. Fir (Abies). 



Pine (Pinus); 2. Douglas Spruce 



2b. Foliage leaves (needles) solitary, not in bundles; mostly less than 25 mm. (1 in.) 

 in length. Mature cones leathery or papery; not hard and woody. (3) 



3a. Leaves jointed near the base, the lower part of the leaf brown and woody and remain- 

 ing on the branchlet after the rest of the leaf has fallen. Leaves in our species stiff 

 and four-angled, not flat. Cones pendulous. Genus 2. Picea 



3b. Leaves not brown nor woody at base, flat. When they fall off they leave a scar but 

 no part of the leaf remains. (4) 



