While coniferous species are the most prevalent types of trees found in Washington State, the region is not devoid of hardwoods. One species of oak is native to Washington as are several kinds of willows, various poplars, some birches and other hardwoods. Washington has a diverse landscape, with the Cascade Mountains dividing the state in two and creating distinct ecosystems in which these tree species grow.
Oregon White Oak
The lone oak species native to Washington is the Oregon white oak, a tree that according to the Washington State University Extension website grows in western parts of the state and in the valleys of the Columbia and Yakima Rivers. Oregon white oak grows slowly, which keeps many people from considering it for landscaping purposes. The tree can be as tall as 70 feet and will grow in numbers, even on rocky soil that will not support other types of trees. Oregon white oak has leaves 4 to 6 inches long with from five to seven lobes that have rounded ends. The gray-brown bark develops fissures as the tree ages.
Rocly Mountain Juniper
Washington is home to the Rocky Mountain juniper tree, a small species that struggles to reach heights of 30 to 40 feet and is more often than not no larger than a shrub. Rocky Mountain juniper grows mostly in eastern Washington but some does exist in the areas of the eastern sections that do have some dry weather. This juniper features reddish wood, red-brown bark, a fruit-like cone and scale-like foliage that is a dark green color. The fact that Rocky Mountain juniper will grow at elevations up to 9,000 feet and in nearly every soil type makes the tree a good choice as an ornamental species. Plant Rocky Mountain Juniper in full sun.
Washington's red alder is a vital hardwood species whose wood is used for pulpwood, furniture and fuel. The red alder grows as tall as 130 feet, but few will attain that size, and most will top out around 50 feet high. The red alder grows fast, has a very shallow root system and possesses 3- to 5-inch long dark green leaves. Red alder grows abundantly in western Washington, typically along roadways. The tree will be among the first types to start to grow in an area scorched by fire or cleared by loggers, growing where the soil is rich and moist in full sun. The flowers produce a small fruit resembling an oblong cone that contains the seeds.
Noble fir grows on both the eastern and western slopes of the Cascade Mountains in Washington and nowhere else in the state. Noble fir is the largest of the fir trees in Washington, a group that includes the subalpine fir, the Grand fir and the Pacific silver fir. Noble fir can reach 200 feet high and have a trunk width up to 7 feet. Noble fir has very thin bark, making it susceptible to the effects of fire, and the older specimens will die from attacks by wood fungi. Noble fir needs full sun to flourish and will grow in damp ground or in rocky soils. The cones are between 4 and 6 inches in length, and the four-sided bluish-green needles can be 1 1/2 inches long.