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.
* * *
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.
Salal is a low-growing, leathery-leaved evergreen shrub that tolerates a wide variety of conditions. Its dark blue “berries” (actually swollen sepals) are edible raw and can be made into jams, preserves, and pies. Salal berries are mildly sweet, and are often used in combination with the more tart Oregon grape.
In the Willamette Valley, salal prefers full to partial shade. In coastal areas it can form deep, nearly impenetrable thickets, and easily tolerates full sun. It grows as far north as Baranof Island, Alaska.
Salal leaves are also harvested and sold to florists worldwide for use in floral arrangements.
Oceanspray is native to western North America, most commonly found in the mountains of the Pacific Northwest. This fast-growing deciduous shrub gets 8-10′ tall and 3-7′ wide. Its small toothed leaves are 2-4 inches long. Cascading clusters of white flowers drooping from the branches give the plant two of its common names, oceanspray and creambush. The flowers have a faint sugary scent, and each one bears a small, hairy fruit containing one seed which is light enough to be dispersed by wind.
Oceanspray is found in a variety of habitats, from wet coastal forests to drier, cooler mountain peaks further inland. It often grows in areas dominated by Douglas-fir. The plant is found in areas prone to wildfire, such as chaparral communities. It is often the first green shoot to spring up in an area recovering from a burn or logging.
Many small solitary bees, bumblebees, and native butterflies visit this plant for nectar. It can also be considered a pollinator “nursery”, as pale swallowtail, spring azure, Lorquin’s admiral, and brown elfin butterflies all lay their eggs on it.
These attractive shrubs thrive on dry slopes in sun to part-sun, and spread well in favorable conditions. Long-leaf Oregon grape and salal do well in their shade, and they pair well with hazelnut to make a woodland border. Combine with red-flowering currant or vine maple for a deciduous screen.
Oxalis oregana, also known as Redwood sorrel, is a species of the wood sorrel family, Oxalidaceae, native to moist Douglas-fir and Coast Redwood forests of western North America from southwestern British Columbia, Washington, Oregon, and California. This attractive groundcover can spread vigorously when planted in favorable conditions.
It is a short herbaceous perennial plant with erect flowering stems 5-15 cm tall. The three leaflets are heart-shaped, 1-4.5 cm long on 5-20 cm stalks. The inflorescence is 2.4-4 cm in diameter, white to pink with five petals and sepals. The hairy five-chambered seed capsules are egg-shaped, 7-9 mm long; seeds are almond shaped.
Oregon oxalis photosynthesizes at relatively low levels of ambient light (1/200th of full sunlight). When direct sunlight strikes the leaves they fold downwards; when shade returns, the leaves reopen. This process only takes a few minutes and the movement is observable to the eye.
The tangy leaves of Oregon oxalis were eaten by Native Americans, probably in small quantities, since they contain mildly toxic oxalic acid (hence the genus name).
Polystichum munitum (Western Sword Fern) is an evergreen fern native to western North America, where it is one of the most abundant ferns occurring along the Pacific coast from southeast Alaska south to southern California, and also inland east to southeastern British Columbia, northern Idaho and western Montana, with isolated populations in interior northern British Columbia, the Black Hills in South Dakota, and on Guadalupe Island off Baja California.
The dark green fronds of this fern grow several feet long at maturity, in a tight clump spreading out radially from a round base. They provide year-round wildlife shelter and visual interest, especially when paired with woodland companions such as Oregon oxalis, inside-out flower, wild ginger, deer fern, etc.
Their preferred habitat is the understory of moist coniferous forests at low elevations. They grow best in a well-drained acidic soil of rich humus and small stones, but can tolerate some clay. Sword ferns are very tough, and can survive occasional dry periods once established. They prefer shade but can tolerate some sun. Their thick root systems and broad spreading fronds make them excellent plants for erosion control.
In favorable conditions, sword ferns produces lush vegetation, and a thick layer of past years’ fronds will accumulate beneath. This material provides winter shelter for wildlife and creates a natural mulch, but these plants tolerate mild pruning to remove dead standing stalks. They also tolerate an occasional full winter pruning to encourage fresh new growth.
A delightful, hollyhock-like perennial rarely found outside its native Oregon, and not in every county. Stands of this perennial have been reported in Washington, Multnomah, Yamhill, Benton, Linn, Lane, Douglas, Coos and Jackson counties, but not all are documented.
This plant is not a true grass but has a grass-like appearance as it is low-growing with long, thin leaves. They often grow on grasslands and resemble iris, a close relative. The flower is a deep bluish-purple to blue-violet and rarely white. The fruit is a dry dark or pale-brown capsule with one to several seeds in a locule. It blooms from March to May and is quite variable.
Douglas Aster is a tall spreading perennial that blooms into the late summer and thrives on saltwater shorelines. The rather lanky stems are topped with bluish purple flowers that look like miniature daisies (ray flowers). The prolific blooms will draw lots of butterflies.
