Juniperus occidentalis (Western Juniper and Sierra Juniper) is a shrub or tree in the Cupressaceae family native to the western United States, growing in mountains at altitudes of 800-3,000 meter (rarely down to 100 meter). The shoots are of moderate thickness among junipers, 1-1.6 millimeter diameter. The leaves are arranged in opposite decussate pairs or whorls of three; the adult leaves are scale-like, 1-2 millimeter long (to 5 millimeter on lead shoots) and 1-1.5 millimeter broad. The juvenile leaves (on young seedlings only) are needle-like, 5-10 millimeter long. The cones are berry-like, 5-10 millimeter in diameter, blue-brown with a whitish waxy bloom, and contain one to three seeds; they are mature in about 18 months. The male cones are 2-4 millimeter long, and shed their pollen in early spring. Western Juniper is slow growing; large trees are very old. In the garden it should be treated as a shrub.