Picea pungens (P. pungens) is an evergreen tree that is mostly regarded as the “Christmas tree”. It is native to the western United States and be found throughout mountain ranges, It has a very long lifespan and it has been documented that the oldest blue spruce can be found in Colorado, with 126 feet (38.4 n) tall with 60.8 inches (154.5m) d.b.h (diameter at breast height). States like Colorado (1939) and Utah (1933) adopted blue spruce as their state trees.
Distribution
It can be found in Idaho, Wyoming, Utah, Colorado, Arizona and New Mexico Mexico. In Utah, it is found at elevations between 6,000 and 9,000 feet. The best sites for these trees are moist, sunny locations. Colorado blue spruce is not shade tolerant but thrives better in dry soils than most other spruce.
Natural History and Disease
Blue spruce is affected by a number of diseases and insects. The most serious disease problem is cytospora canker, a fungus which lives in the trunk and branches of Colorado blue spruce. The disease starts low on the tree and spread its way to the top gradually. While this is the most serious problem of Colorado blue spruce, this tree is also affected by several needle diseases like pine needle scale and insects such as the white pine weevil. When planted as windbreaks, the Colorado blue spruce is also very susceptible to herbicides.
Colorado blue spruce can live 200 years or more.
Significance
• Economic
o Not a very important tree even if its big tree trunk and wood is considered very brittle
• Wildlife
o Food – Birds eat its seeds; also favorite for squirrels
o Cover – Provides cover for birds and big game animals like deer, mule and many small non-game animals
• Others- Blue spruce is used as a windbreak or ornamental tree because of its blue color from the powdery, waxy layer (glaucous) on the needles. Lifespan as a windbreak or ornamental tree is about 40 to 60 years. One interesting fact is the blue property of the tree is under genetic control to maintain its interestes to the public.
Habitat Types and Plant Communities
• Scattered setting: Blue spruce occurs as dominant or co-dominant
• Riparian settings: Blue spruce is co-dominant with cottonwoods such as narrow leaf cottonwood
• Rocky Mountains: Blue spruce is more important in habitat type.
• Southwestern mixed-conifer forests: Restricted to cool, moist areas. Common co-dominants are Engelmann spruce, white fir, and Douglas-fir.
Name and Taxonomy
• Group: Gymnosperm
• Duration: Perennial
• Family: Pinaceae
• Genus: Picea
o comes from Latin and means pine, spruce or fir.
• Species: pungens
o from Latin, means “to sting”.
• Navajo Name: ch'odee ni'nii
Foliage
• Evergreen
• 3/4 to 1 1/4inches (2 to 3 cm) long
• 4-sidedneedles that are dull green to silvery-blue
• Stiff and very sharp
• Borne on a raised, woody peg
Flower
• Monoecious
• Male: Reddish brown; Yellowish brown when ripe; found all throughout tree
• Female: Purple, upright in top of tree
Fruit
• Cone: Mature in fall
o Male: Orange
o Female: Green
• Cylindrical when mature; 2-4 inches long with papery scales
Pollen
• Wind-borne
Twig
• Gray with loose, thin attached scales
• Hairless, tan
• More stout than other spruces
Bark
• Gray to red-brown
• Young trees: Small, thin scales;
• Older trees: Scaly but with shallow furrows
Form
• Medium to large tree with pyramidal form reaching up to 80 feet tall