Western Juniper (Juniperus occidentalis)

Location: Just north of Kane Hall at the corner of Spokane Lane and Chelan Lane.

Summary: There are relatively few Juniper trees on the UW Campus, especially considering that this genus of trees is one of the most widespread in the world, occupying sites from the frigid shores of Greenland to the scorching deserts of Africa. The species showcased on this tour, the Western Juniper, is the largest of the North American Junipers. On rocky sites in the Sierra Nevada mountains of California, this species can achieve heights of 80’ and many measure over 12’ in diameter. Here in Washington, specimens generally achieve a more modest size, but every inch they grow is a miracle in itself due to the extreme nature of the habitat in which they are found. The Western Juniper can tolerate as little as eight inches of precipitation in an average year, making them the most drought-tolerant tree species in the state. Survival in such an environment requires careful conservation of resources and limits growth, and it is not uncommon for a Juniper less than two feet in diameter to be closing in on its 1000th birthday. Some specimens are known to be at least 1,600 years of age, but it is quite possible that the oldest surpass the 2,000-year mark. Because the largest individuals often have heart rot, a count of yearly growth rings for these individuals is an underestimate of true age. The species is sensitive to fire, which often destroys stands entirely. A Western Juniper forest can take over 150 years to reestablish following a burn. 

Western Juniper is one of four species in the Juniperus genus found in our state, along with the Common Juniper (J. communis), Rocky Mountain Juniper (J. scopulorum), and Seaside Juniper (J. maritima). Juniper is important as a traditional medicine in many parts of the world for the treatment of colds, coughs, fever, pains, rheumatism, diabetes, and more. The berry-like cones can also be used as a food (cooked or roasted), and the bark can be used as tinder for fire starting. Early colonizers prized the dense rot resistant wood for fence posts and firewood (leading to the destruction of many ancient specimens). In modern times, the fire suppression practices of Euro-Americans have led to a widespread expansion of Juniper forests in many arid places of the American west

Identifying Features light: A smaller tree, the Western Juniper occupies drier sites up and down the western mountain ranges. Differentiating between different species of Juniper can be immensely difficult, as they share many of the same traits. This species has gray-green glandular foliage (with small holes on the leaves), with overlapping foliage, i.e. each small leaf overlaps the next in pairs and threes. They generally reach a height of 20-30 feet in height and a trunk girth of 2-3ft (although many specimens are stunted to the size of a ground shrub in more extreme environments). Often the cinnamon colored trunks are twisted and gnarled by the extreme environment they prefer, and it is not uncommon for multiple trunks to be present. The fruit of this coniferous evergreen are blue-black berries about a quarter inch in diameter with a tough resinous skin protecting 2-3 bony seeds. This is a relatively young specimen of a tree seldom seen in western Washington, but their native ranges they may live a thousand years or more.

Identifying Features In Depth:

1. Form: A smaller tree, often with multiple trunks due to a harsh native environment, generally growing to 20 or 30 ft (6-9m) in height but in known to reach a height of 78ft (25m) in one case. In the harshest settings they spread like a groundcover, seeming more as a low bush than a tree.

2. Leaves: Leaves of this tree are scale like and overlapping, gray-green in color and have distinctive gland pits on the back (a feature which helps distinguish them from other junipers and is clearly visible on this specimen). They are arranged alternately in pairs or threes and fringed with fine teeth.

3. Bark: Bark of this tree is cinnamon colored and stringy in nature, arranged in long diagonal fissures. On older specimens it is not uncommon for the reddish brown or light wood to be exposed by missing patches of bark.

4. Reproductive Bodies: The Juniper, although a conifer, produces berries of a blue to black color and containing between 2 and 3 hard seeds about 1/8 of an inch long (0.3 cm) with deep grooves on the back. The berries are round with a thick skin and thin resinous flesh, usually about a quarter to a third of an inch in diameter (0.6-0.8cm).

Historical Background: A hearty specimen, the Western Juniper occupies a harsh and unforgiving niche. In the desert it grows on dry sites facing blistering heat and drought, while in the mountains of California is faces the prospect of heavy snows deep enough to bury a good size specimen entirely. Junipers in general are a widespread group, the most common woody plant in the northern hemisphere in fact. As a result, they have been used by humans for a wide variety of purposes, perhaps the best known being the production of Gin from Juniper berries. In North American, indigenous peoples used the berries as a diuretic, and they were incorporated into treatments of diabetes, as well as for contraceptive. They were used by the Paiute for sore throats and colds, and as food. In contemporary times, timber of these sculptural trees was found by ranches to make exceptional fenceposts due to the slow rate of their decay, though the wood is far to gnarled and knotty to make it profitable as a source of timber for construction. This is perhaps a blessing, since the tree takes at least 20 years to become reproductively active and may take as many as 50 to produce a good crop of seeds. The largest specimen of the Western Juniper near Sonora Pass in California is thought to be more than 3000 years old. The berries are a food source for many small mammals and birds, who eat them and disseminate the undigested seeds in their droppings, including those of Robins and Coyote. Fruit takes 2 years to mature, so the ripe must be picked out from new growth. The berries (which are actually cones since this is a conifer) act as an important winter food source, especially in the rugged niche this tree thrives in.

Native Range: A rare tree in Washington State, it occurs southeastern portion of the state in the high desert plains. South of Washington it becomes more common, occurring in the empty country of eastern Oregon as well as on the slopes of the Cascades (although it is rare on the west side). It occurs readily on both sides of the Sierra Nevada and grow to elevations above 10,000 feet in that range and in the San Bernadino Mountains to the south of it.