Western Juniper

(Juniperus occidentalis)

Color Photographs: © by and courtesy of Charles Webber, California Academy of Sciences

Western Juniper (Juniperus occidentalis Hook.)

Identifying Characters: The northern and western range of the species, the toothed fringe of the scales, and the blue-black berries with a white bloom will usually separate this species from other junipers.

Similar Species: California Juniper may be found with Western Juniper. The berries of California Juniper are red-brown with a grayish bloom. The berries of Western Juniper are blue-black with a whitish bloom. The berries of California Juniper are 0.5 to 0.75 inches in length, but those of Western Juniper are 0.25 to 0.4 inches in length. Western Juniper is easily confused with Utah Juniper. The berries of Western Juniper are blue-black without a reddish tinge. The berries of Utah Juniper are also blue-black, but do have a reddish tinge. The foliage of Western Juniper is conspicuously glandular, but that of Utah Juniper mostly lacks glandular dots. The bark of Western Juniper is primarily red-brown, but that of Utah Juniper is gray.

Measurements: A tree with low, spreading branches; crown either spreading or round; height of mature trees between 20 and 40 feet; diameter at breast height 1 to 3 feet.

Female Cones: Cones berry-like, round, 0.25 to 0.4 inches in diameter; color blue-black with a whitish bloom; texture soft and juicy; 2 to 3 seeds.

Leaves: Leaves scale-like, mostly in groups of 3; about 1/16 inches in length; foliage with round twigs; scales with a toothed fringe at 20x; color gray-green; scales with a glandular dot.

Bark: Bark red-brown, fibrous, furrowed, and shredding.

Native Range: Western Juniper is found intermittently from latitude 34° N. in California to latitude 46° 37' N. in southeastern Washington, in a narrow belt from longitude 117° W. in Idaho and California to longitude 123° W. in northern California, and in sparse, scattered stands in south-central and southeastern Washington, southeastern Oregon, and the northwest corner of Nevada. In southwestern Idaho, it grows on approximately 162 000 ha (400,000 acres). Western juniper reaches its greatest abundance as extensive and continuous stands in central Oregon. Stands more limited in size extend up the valleys and foothills of the southern Blue Mountain region, and small groups or individuals are scattered sparsely through the northern Blue Mountains. Extensive stands are common on the plains and in the foothills of north-central Oregon, and large stands occur down the high plains and foothills of south-central Oregon. From north-central through south-central Oregon, western juniper grows in various densities on roughly 1 140 000 ha (2,816,000 acres). It is found near Mount Ashland in southwestern Oregon, the only native stand documented west of the Cascade Range in Oregon. It grows in scattered locations west of the Cascades in northern California and extends south to Trinity County. Western juniper is present in extensive stands from the Oregon border south through the Pit River Valley in northeastern California and continues intermittently as sparse stands in a narrow corridor along eastern California south to disjunct stands in the San Bernardino Mountains. The eastern limits of this species are in San Bernardino County, California, and Owyhee County, Idaho. The western limit is Trinity County, California (Silvics of North America. 1990. Agriculture Handbook 654.)

Habitat: Western Juniper occurs primarily on dry mountain slopes or plateaus, usually on rocky soils.