THE SILVA OF COLORADO IIQ 



Montana to southern Colorado, west to California and north to Alaska. This 

 tree is found, as a rule, at higher elevations than the rock pine. 



Genus PICEA, The True Spruces 



Tall, conical, evergreen trees with tapering trunk and thin, scaly bark. Leaves 

 needle-shaped, four-angled or flattened (ours four-angled) with sharp points. The 

 leaves extend out from all sides of the twig in bottle-brush fashion; they are not in 

 bundles as in pine but occur singly. Leaves jointed near the base, the lower part 

 (sterigma) becoming woody and persistent after the fall of the leaf. Bare twigs 

 thus appear roughened with short, truncate elevations. The stomata (pores) on 

 the leaf surface may be seen with a good hand lens as white dots occurring in rows. 

 Staminate flowers axillary; the carpellate terminal. Cones pendulous, the cone 

 scales somewhat papery when mature. About i8 species all in the colder and tem- 

 perate parts of the northern hemisphere. Various species are planted for ornament, 

 or as windbreaks in exposed places. 



Key to the Colorado Species of Picea 



A. Leaves rigid, needle pointed, blue-green or silvery, branchlets smooth or at 

 least not hairy. Cones about 7 cm. (af in.) long. Frequent in cultivation. 



I. Picea parryana 



B. Leaves less rigid, abruptly pointed, having a somewhat skunk-like odor when 

 bruised. The branchlets are generally described as pubescent but are smooth 

 in specimens grown at high altitudes. Cones about 4 cm. (if in.) long. 



2. Picea engelmanni 



Picea parryana (Andree) Sarg. Blue Spruce, Colorado Blue Spruce 



Rydberg, Flora Colo. 8; Coulter, Manual 431 (as Picea pungens); Sargent, 

 Manual Trees of N.A. 44; Nelson, Key to Rocky Mountain Flora 6. 



Leaves stout, rigid, four-angled, mostly 25 to 30 mm. long but on cone-bearing 

 branches shorter and curved. Generally the leaves stand out from all sides of the 

 branchlets but sometimes the under surface of horizontal branches has few leaves. 

 Stomata (pores) in 4 to 7 rows on each of the four surfaces of the leaf. Color of 

 leaves generally silvery or bluish-green when young, becoming duller with age. 

 Individual specimens differ greatly in this regard. Cones about 7 cm. long; the 

 cone scales rhomboid; corrugated; rounded or truncate at apex or sometimes with 

 a few teeth. 



A tree of medium size. Until the age of 30 or 40 years it forms a broad-based 

 pyramid but later the lower branches die and the top may become ragged with 

 branches rather far apart. Bark broken into small oblong, platelike scales; on 

 old trunks thick and deeply grooved. Wood light, soft, weak; specific gravity 

 0.3740. 



