Alnus rubra

Red alder (Alnus rubra) is a fast-growing deciduous tree that does well in open areas and along streams. This slender, medium-sized tree can grow 5′ or more a year for the first few years, and generally grows to 40-50 feet tall, sometimes reaching as high as 80 feet.

Red alder blooms in March, putting out long, rounded, dangling clusters of reddish-orange flowers called catkins. Leaves turn a slight golden color in the autumn. In the open, alder crowns form a lovely rounded shape with spreading branches.

This tree plays many roles in forested landscapes. Deer and elk browse on the leaves, buds, and twigs. The seeds are important winter food for birds such as redpoll, siskins, goldfinches, and others. Red alder provides food for the young of swallowtail and mourning cloak butterflies, and stands of this tree provide shade for a variety of forest understory plants such as osoberry, vine maple, and sword ferns.

This tree does best in sun to part shade with moist soils. Plant it for fast-growing shade and screening.

Arbutus menziesii

Madrone is an attractive, broad-leaved evergreen tree with a twisting trunk that develops beautiful reddish-brown exfoliating bark with age. Mature size ranges from 20 to 65 feet tall and wide. Madrone does best in full sun and grows well on hillsides with dry, well-drained or rocky soils. Leaves are dark, shiny green and shed irregularly throughout the year.

Flowers are small, pinkish, and bell-shaped, arranged in drooping clusters. Flowers appear in April, followed by small round orange-red berries. Madrone’s fruit is eaten by a wide range of birds and its flowers attract numerous pollinators. They reach their full aesthetic potential when planted in a grove. Madrones can be difficult to establish, so plant small seedlings and be patient.

Betula papyrifera

Paper birch (Betula papyrifera) is a medium to fast growing deciduous tree, reaching a mature height of 50-70 feet. The leaves are simple, alternate, to 4 inches long, toothed and roughly egg-shaped, coming to a pointed tip. The leaves turn bright yellow in the autumn. Flowers are male and female catkins to 1½ inches, blooming in the spring.

Paper birch is a widespread North American species; on the West Coast, the birch is considered native from eastern Oregon to Alaska. Paper birch is known for its distinctive bark, which is whiter than many birches and peels in papery strips. The bark of the birch was used for canoe-making across the United States outside of the Pacific Northwest (in the Pacific Northwest, Western redcedar is more commonly used). Traditional uses for birch resin include medicine, adhesive, and chewing gum. Today birch is a commonly used for pulp wood and as an ornamental tree.

Because all birches attract aphids and their “honeydew,” the tree is not recommended for patios or parking areas.

Calocedrus decurrens

Incense cedar is a conifer native from central-western Oregon through most of California. It has a distinct symmetrical shape and can get up to 90 feet tall in its native habitat.

The bark is orange-brown weathering grayish, smooth at first, weathering to grayish, fissured bark that sheds in long strips on the lower trunk on old trees. The fragrant, bright-green foliage is produced in flattened sprays with scale-like leaves. The seed cones look like the open beak of a duck. They turn orange to yellow-brown when mature about 8 months after pollination.

Many birds depend on insects that live on incense cedar, including woodpeckers, brown creepers, red-breasted nuthatches, and golden-crowned kinglets. Birds use the dense foliage for nesting in the summer and shelter in the winter. This tree is also the preferred host of a wood wasp, Syntexis libocedrii, a living fossil species which lays its eggs in the smoldering wood immediately after a forest fire.

Cultivation and Uses

The wood is the primary material for wooden pencils, because it is soft and tends to sharpen easily without forming splinters. It is also a popular ornamental tree, valued for its drought tolerance. In cool summer climates (such as in Washington, British Columbia, etc.), incense cedar tends to grow narrower than in the wild, making it a good choice for large hedges and screens.

Fraxinus latifolia

Note: Due to the recent arrival of emerald ash borer in Oregon, ash trees in our region are at high risk of mortality over the next several decades. See OSU Extension Service’s emerald ash borer resources page for more information about how you can slow the spread and protect your ash trees.

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Oregon ash is native to western North America on the west side of the Cascade Range from southwestern British Columbia south through western Washington and western Oregon to central California.

It can grow to 80 ft in height, with a trunk diameter of 3ft. The leaves are pinnate, 3.5-10″ long, with 5-9 ovate leaflets. The fruit is a samara, 3-5 cm long including the wing. The leaves turn a striking yellow in the fall.

Oregon ash prefers damp, loose soils, and grows from sea level to 900 meters. It is a dominant tree in local forested wetlands, paired with an understory of spiraea and slough sedge.

Oregon ash is an ideal deciduous tree to plant along streams, seeps, and wet areas. It forms an attractive shape, tolerates saturated soils, and shades waterways.

Pinus ponderosa

Willamette Valley Ponderosa Pine (Pinus ponderosa var. benthamiana) is a beautiful tree with long needles and attractive bark. Like all ponderosas, the bark of this tree has a vanilla-like scent when warmed by the sun–and they love sunny spots! However, the Willamette Valley Ponderosa is the only variety of ponderosa that can also withstand the heavy wet winter soils of our region.

This long-lived tree is very valuable for wildlife. Its needles are the only known food for gelechiid moth (Chionodes retiniella) caterpillars. Many species of birds and small mammals eat the nutritious seeds and use the needles for nesting material; others use cavities and branches for nesting and shelter.

Willammette Valley Ponderosa Pine is one of four different varieties of Ponderosa Pine, each adapted to different climatic conditions and with differing botanical characteristics. When planting in Multnomah County, it is very important to use this variety, as it is the only one that will thrive in our region.