Springbank Clover. Fascinating perennial clover that was once widespread in wet areas of the Willamette Valley and is now found in restricted sites there but is much more prevalent on the coast and east of the Cascades. A pretty spreading spring wildflower with heads of brilliant magenta/purple flowers. Mainly in spring but also in summer if wet. To 4″ tall it can be up to 2′ wide in favorable conditions. Though mostly restricted to seeps and wet areas now it once made life under native white oaks and there indigenous people would use it as a food source. The creeping green stems root where they touch the ground. Stems were harvested and steamed as a vegetable and they replanted as they harvested the remaining stems ensuring another crop. Not a long lived perennial 3-5 years but it sets copious seed. Wet sites in moisture retentive soil. Mainly riparian in habitat. It can dry considerably in summer and still thrive. But regular water is what it wants. Fun plant to grow that has lost a LOT of its native range. In habitat it is best seen on the wet cliffs adjacent to the beach. Great pollinator plant. Easily overwhelmed by invasive exotics. Oregon native plant.
Biome: Willamette Valley Natives
The Willamette Valley is not only Oregons most populous region it is a landscape in flux. What was open grassland and oak woodland managed by fire by the initial residents was densely settled, farmed and logged by Europeans. No where in the state are human pressures so close to fragile nature.
Xeric clay soils
The Willamette Valley is comprised of xeric clay soils. These soils are dry in summer and biological activity ceases as the dry season sets in. These soils require diligent attempts to rehydrate once they have dried. Often the water just beads up and rolls along the surface of the soil (hydrophobic). In soils like this mulch of any kind is paramount.
A distinct dry season
This pronounced dry season is a hallmark of the valley biome. Beginning in June and progressing into early autumn high pressure inhibits almost all precipitation. The natives in this landscape including many annuals, perennials and bulbs that are native to California are also native in the Willamette Valley but not north of the Columbia River. Many plants are found and many are endangered only in the valley. The center of the genus Sidalcea finds a home and diversity no where else.
Introduced exotics snuffed out many natives
Its important to remember that there were NO RUNNING or stoloniferous grasses native to the Willamette Valley. Only clumping grasses with space between for such things as native annuals and perennials. When turf grasses were introduced for ornamental and commercial purposes they pretty much snuffed out most of the native habitat of many forbs (herbs). Wild flower habitat was destroyed. Add to that rambunctious exotics such as Armenian/Himalayan Black Berry and Scot’s Broom and European pear and more exotics and the space for many of these natives is squashed. We include plants that are native adjacent to the valley too and perform wonderfully here.
Oregon’s most endangered biome
Most of the Willamette Valley was occupied by Oregon Oak Savanna. This is Oregon’s most endangered biome and attempts are being made to set aside the less than .06% that is left(!) We encourage local gardeners to welcome the wealth of wildflowers native to the Willamette Valley. They are in serious peril.
Climate adapted plants for gardeners in the PNW
Trillium albidum
Giant Trillium or Great Western Wake Robin, I think the first name is the most common. This sweet large woodland Trillium inhabits moist woods in the valleys of the western side of the Cascades. Its sporadic in occurrence but when you do stumble upon it in the woods its often very profuse. The stature and individual leaf size are what give this somewhat subtle flowered perennial its name of Giant Trillium. It is very easy to tell aside from western Trillium, T. ovatum. which is a smaller daintier plant with larger white flowers that normally senesce to pink/red before falling apart. Giant Trillium has much smaller individual creamy white flowers and they almost appear as an afterthought in the center of the large leaves which can appear initially with black mottling that then fades. To 2′ tall and increasing to form large patches in vernally moist woods. Giant Trillium goes dormant by mid summer and there is no presence until the following spring. Beware deer love Trilliums. There are two other sub species of Giant Trillium endemic to the Willamette Valley. This is the most widespread species. Rich, moisture retentive soil in part shade to shade. Oregon native plant.
Trillium kurabayashii
One of Oregon’s greatest wildflowers. This native of the Siskiyous and the SW part of the state makes an outstanding garden plant. Ours are divisions from well marked leaves and flowers with a deep maroon/black hue. To 18″ tall in bloom it responds readily to rich, humus filled soil with regular summer water. In very dry conditions it will go happily summer dormant. And it usually does anyway by the end of the hot season. The black and green leaves are dramatic but a great collar to the tall upright dark flowers. Blooms appear in Portland in April/May and last for weeks. Part shade to shade- avoid blasting hot sun- it will grow in sun but go dormant very quickly. Roots very deep into the ground- difficult to move once established so pick its home carefully. Multiplies into a substantial patch with good care. One of our favorite native wildflowers. Limited quantities. Oregon native plant.
Triteleia hyacinthina
Fool’s Onion, though this close relative of Brodiaea is easy to tell apart from Allium as the leaves and stem have no onion odor. A sunny native perennial bulb that forms colonies of white in May-July in meadows, glens, and swales. To 15″ tall in bloom but usually shorter the leaves emerge in mid winter and persist until summer drought. About that time the flowers erupt into clusters of white flowers. Great native bulb for naturalizing, Water if planting from a pot, otherwise it requires only what falls from the sky with a distinct dry period in summer. Associated plants are Ranunculus occidentalis- Western Buttercup, and Brodiaea elegans- Cluster lily, and Plectritis congesta- Sea Blush. Native in clay soils that dry completely in summer. Goes very neatly dormant in summer- nothing is left. Excellent in rock garden conditions. Full sun to very light shade. Moderate deer resistance. Native though out western Oregon. Sweet cutflower Very good for butterflies as well. This plant once occupied large areas of the Willamette Valley, that territory has shrunk considerably. Oregon native plant.
Vancouveria hexandra
Inside-Out-Flower is a commonly seen terrestrial component in dry to moderately moist woodlands in our region. The duck foot shaped leaves are conspicuous and pretty and in late spring to mid-summer a continuous supply of dainty downward pointing white flowers. Spreads in gardens very well in enriched soil with regular summer water where it will quickly assume the role of an intertwining ground cover. Winter deciduous- un-like its close and much more drought adapted relative Vancouveria chrysantha (Yellow inside-out-flower, Siskiyou Vancouveria). This perennial is perfect for life among shrubs or mixing with other woodland perennials in part shade to shade. Adapts well to garden culture and thrives on regular summer irrigation. Locally native in the city of Portland. To 10″ tall and spreading. Some deer resistance. Oregon native plant.
Viburnum ellipticum
Oregon Viburnum or Western Way Faring tree is a moderate to large native deciduous shrub. It stretches a little bit into W. Washington where it is rare but its primary populations are in western Oregon and south into N. California. Its found in moist to dry woods often on the margin where its can get at least half a day sun. It also thrives only much larger and lankier in outline in the shade. It easily tolerates winter inundation but is found on well developed soils in upland situations as well. Its common associates in the wild are Oregon white oak/Quercus garryana, Oregon Ash/Fraxinus latifolius, Cornus stolonifera. Leaves are round, glossy and scalloped and are very handsome on a well proportioned fountain shaped shrub. Shorter in full sun, taller in shade. This plant needs just a modicum of light watering for its first year and once it is thoroughly established you can set it free. In late spring off white cymes of flowers have the fragrance to me of raw potatoes. We had a large specimen of this shrub in our back 40 where I grew up near Eugene. In certain years it can produce quite a fall show with orange/red tinted leaves and translucent blue fruits. Blooms on wood from the previous year. Prune if needed AFTER blooming has ended. June. To 5′ tall in the sun to much taller in shade. Protect young plants from deer. Oregon native plant.
Viola praemorsa ssp. praemorsa
Canary violet or upland Violet has many subspecies in the PNW and west in general. This is our own Willamette Valley form of this intriguing handsome perennial. Large spoon shaped leaves have an underside with conspicuous hairs. The top of the leaf is glossier. In April-May bright yellow flowers appear. The bottom petal has conspicuous black whiskers. In our region this violet is local in the most undisturbed sites but it shows very good persistence in competition with non-native introduced grasses. My experience is that it favors rocky and scree sites that remain somewhat cool- for instance the north side of a steep slope. To 6″ tall and forming expanding plants. Winter deciduous. Arrives early in spring and can go summer dormant with high heat. Excellent planted in fall or winter and left to its own devices. Average to enriched soil yields the best results. This is one of the showiest violets native to the Willamette Valley. Fairly long lived. Little deer resistance. Some associated plants are Olysinium douglasii, Sedum spathulifolium, Dodecatheon hendersonii. Oregon native plant.
Whipplea modesta
Yerba de Selva or whipple vine, a wonderful small scale evergreen native ground cover. Related to Hydrangeas but this trailer is actually very droughtadapted.e In late spring clouds of small white flowers , Scrambling plant to about 8″ tall and 2′ wide. Full sun to considerable shade. From Portland south this is a common understory component of the herb field. It grew happily in our back 40 where I grew up. There it made pretty scrambling patches between Vancouveria, snow berry and hairy honeysuckle. Often you would see our native columbine ( Aquilegia formosa) as an associate. Its very drought adapted when established but it improves with a few soaks over summer- never perpetually wet and never hot and wet. Otherwise an easy native that should be grown a lot more. For use as a small scale ground cover plant on 10″ centers. It will also gracefully trail over rockeries and walls. Butterflies adore the flowers. Competes well with invasives. Some deer resistance. It may be cut back in early spring to refresh. Once native in the Portland city limits. This is a great native understory for Arctostaphylos, which is frequently seen in the wild. Oregon native plant.
Wyethia angustifolia
Mules Ears are rare in cultivation. These cheery bold perennials make the transition of our wild flowers from spring into real summer. So named for its long leaves it forms very permanent spreading colonies in clay soils in habitat. The brilliant yellow sun flower blossoms rise up on sturdy stems directly from the ground. Each ebullient large flower is about 4″ across. Blooms appear from late April to early June. This plant usually finishes blooming just as summer drought commences. Its a memorable sight in wild meadows where it blooms simultaneously with native Rosa nutkana and Farewell to spring (Clarkia amoena var. lindleyi) and Giant blue eyed mary (Collinsia grandiflora). Wonderful cut flower and immediate and popular pollinator perennial. This plant was once very common in the Willamette Valley but civilization has immensely shrunk its native range. Good, long lived garden plant that goes summer dormant quickly after blooming has ended. The leaves turn gray and brittle and can easily be removed then. Give it a summer rest w/ little to no summer water once established. Full sun to very light shade. Water to establish its first season then none in subsequent years. Fun to grow and LONG lived. To 14″ in bloom forming a plant several feet across. Moderate deer resistance. Native to the Portland city limits. Very slow to finish in a salable size. Patience. Limited quantities. Oregon native plant