Rhamnus purshiana/Frangula purshiana

Cascara is a small tree or shrub ranging from BC through Northern California, and East into Montana. In the Eastern and Southern parts of its range, it adopts shrubby forms, some of which may be distinct subspecies.

The scientific name appears to be in transition. While the Integrated Taxonomical Information System still lists it as Rhamnus, many up-to-date sources (Jepson 2nd. Ed.; WTU Herbarium; USDA database) have elevated the subgenus Frangula (thornless buckthorns with five petals and no leaf scales) to the genus level.

The common name Cascara comes from the Spanish “Cascara Sagrada” or “sacred shell”, named for its medicinal bark. The bark of the Cascara is an effective and relatively mild laxative. It was accepted into the western pharmacoepia until 2002, when the FDA banned it for over the counter use, for lack of studies proving its safety. As it is slow-acting, there is danger of overdose, and long term use can cause habituation. Although there are reports of people eating the fruits, they probably contain some toxins. Parts of the cascara plant are also uesd to produce yellow and green dyes.

Cascara has a high value to wildlife. The Lepidoptera Caterpillar Host Plant Database lists 22 species that use Frangula purshiana. A cascara in flower tends to be full of insect pollinators. Many birds, including grosbeaks, grouse and band-tailed pigeons consume the fruits, as do many mammals. However, it ranks as poor forage for ungulates, making it a relatively deer-proof plant.

Cascara most often grows as an understory tree, easily overlooked if you are not paying close attention, though the reddish bark and long, pleated leaves are quite pleasing. Individuals planted in the sun become much fuller than those in the shade. Since there is a market for the bark, large cascaras are rare in the wild. Many harvesters peel off the bark from a standing trunk. This kills the tree. Cutting the tree down and leaving a tall stump allows for substantial bark harvest, and allows the tree to grow back, albeit in a coppiced form.


Cornus Sericea

There are three species of Cornus (dogwood) native to Washington State; Cornus nuttalii is a tree; Cornus unalaschkensis is a 4” ground cover; and Cornus sericea is a shrub.
Redtwig (or red osier) dogwood ranges over most of Canada and the U.S., being absent from only the SE corner of the United States. There are two recognized sub-species, ssp. occidentalis, found along the West Coast, and ssp. sericea, found throughout the species range. Ssp. occidentalis has ridged stones, generally hairier leaf undersides, and slightly larger flowers; ssp. sericea has smooth stones, glabrous to strigose leaves, and slightly smaller flowers (Jepson). Hitchcock posits that these traits form a continuum rather than two distinct forms.
Cornus sericea is a stoloniferous wetland shrub, tolerant of saturated soils, and even of some standing water. It has excellent soil binding capabilities. Horticulturally, it is popular for its bright red twigs in winter (It is often coppiced to enhance their effect). There are many cultivars available, most chosen for the color of their twigs.
Redtwig dogwood has clumps of small, white flowers in late spring that are an important nectar source for butterflies, and it is a larval host for the Spring Azure (Celastrina echo), which lays its eggs on the flower buds. Many bird and mammal species eat the berries, and help in seed dispersal. (Bears are purported to love them). The stems are an important browse for ungulates, and stands can be heavily affected by cattle grazing.
While the berries are bitter to humans, some native peoples did use them as food. Cornus sericea is also used in traditional medicine, and the twigs are used in basketry.

Alnus Rubra

Red alder is another iconic Northwest Coast lowland plant. It ranges from Southern Alaska in the North to Santa Cruz County in the South, mostly on the West slope of the Cascades, though there is a disjunct population in far Eastern Washington, Central Idaho and Western Montana. It is the largest species of Alder in North America (a recent champion tree, in Clatsop County, OR, was measured at 104′ height, 49′ spread, 245″ circumference).

Red alder is a short-lived, early-seral species; its seeds are both wind pollinated and wind dispersed, and its seedlings do best on bare mineral soil. It is difficult to propagate vegetatively. Young red alders grow very quickly, but rarely reach their hundredth year. Red alder is tolerant of saturated soils, but not of drought.

Alnus rubra is actinorhizal. It a forms a symbiotic relationship with an actinomycete filamentous bacterium in the genus Frankia, which has the ability to fix atmospheric nitrogen. The relationship begins with an intracellular infection of a root hair, which leads to cell division in the pericycle, eventually growing a multi-lobed root nodule. Both the roots and the leaf litter significantly increase the amount of available nitrogen in the soil. Douglas fir grows faster in conjunction with red alder than without it.

Red alder has also become the most important commercial hardwood in the PNW. Although the wood rots quickly out of doors, its workability makes it a favorite for furniture, cabinetry, and toymaking. Red alder is not a chosen browse of most ungulates (deer will preferentially eat dropped leaves in the fall, but avoid them on the tree), but the bark is an apparent delicacy for mountain beavers. Red alder trees are an important winter forage for pine siskins, chestnut backed chickadees, and kinglets. Sapsuckers are considered a pest of commercial stands; their feeding holes damage the wood, sometimes even girdling the tree, or weakening it to the point that the top blows out in a storm.

Amelanchier alnifolia

Serviceberry, Saskatoon, Juneberry, shadblow, (among many common names) is a widespread and variable shrub or small tree. A. alnifolia, the species found in the Puget Lowlands, ranges in a widening triangle from Southern California through the West, and over most of Canada. Because of its variability, some authors have split A. alnifolia into several species. Hitchcock and Cronquist list five varieties, but note that “features vary independently rather than in tandem.” A. alnifolia var. semiintegrifolia is the subspecies
found here in the Central Puget Sound region.
Saskatoon berries are grown commercially in Canada and in some parts of the US, and their nutritional properties are similar to blueberries, leading some people to advertise them as a “superfood.” In addition to eating the berries (fresh or dried,) Native Americans used them as a sweetener and preservative for other foods. The twigs were made into medicinal tea, and the wood was used for combs and arrows, or whenever a hard, straight wood was needed.
Many varieties of wildlife partake of the fruit of the serviceberry. Ungulates (especially elk) browse the twigs, though their high cyanide content can be deadly if no other food is available. Butterflies, bees and hummingbirds nectar on the flowers, and it is a caterpillar host plant to pale tiger swallowtails, lorquin’s admirals, hairstreaks and elfins.
With white flowers in the spring, delicate bluish-green foliage, colorful berries, and yellow to orange fall color, A. alnifolia may be used as a specimen in a small garden, and it is a welcome addition to a naturalized border. It tolerates some shade, but full sun will maximize fruit production. It can be propagated by transplanting suckers, layering, softwood cuttings or seed, though seed viability is reported to be low. It is widely used in restoration sites because of its value to wildlife, drought tolerance, and soil-binding capabilities.

Sisyrinchium californicum

This month I have a flower request from the folks at the plant sale. Yellow-eyed grass is one of the two common species of Sisyrinchium native to Western Washington. It ranges mostly along the western slope of the Cascades from BC South through California. A lover of damp places, it can be found at the edges of wetlands, along seeps, and in wet meadows.
Sisyrinchiums are members of the iris family. The name comes from Theophrastus, although the modern usage applies to a New World genus. Sisyrinchium have their center of diversity in Argentina, and genetic evidence seems to point to two separate waves of expansion into North America. Sisyrinchium idahoense (blue-eyed grass), our other common Sisyrinchium here in Western Washington, comes from a different branch of the genus than californicum does. There are also a couple of endemic Sisyrinchiums in the state that may have speciated from the more common varieties during an ice age.
In the garden, it is a short-lived perennial that re-seeds in damp spots (like the well-watered beds in the nursery). Usually less than a foot tall, the symmetrical yellow flowers that peek out between the strap-shaped leaves open on sunny mornings and often close by afternoon. When not in bloom, it forms pleasing clumps of pale green mini-iris. The dry leaves turn a purplish black, providing a nice contrast.
Lisa Karst, Ph.D. Phylogeny, Character Evolution, and Biogeography of Sisyrinchium (Iridaceae)