Unlike the proverbial human wallflower, the Pacific Northwest’s native wallflower plant (Erysimum capitatum) isn’t shy or modest. Instead, it is bright, showy, sweetly fragrant, and attractive to pollinators like butterflies and bees. Although it didn’t make it into my book, it is definitely worthy of praise and recommendation.
The genus Erysimum, a member of the cabbage (Brassicacaeae) family, contains about 150 species found throughout much of the northern hemisphere. Growth habits may be annual, short-lived perennial, or woody perennial. Carl Linnaeus named the genus after the Greek word eryomai, which means “to help or save” in reference to the medicinal qualities of several species. European folk medicine practitioners used poultices of wallflower for bronchial congestion, while Native Americans made tea with the dried leaves or seeds of wallflower to relieve stomach cramps.
In the U.S., western wallflower (aka prairie rocket, Douglas wallflower and sand dune wallflower) occurs in many different habitats throughout the west, including parts of Washington, Oregon, California, and southern British Columbia (usually below 4,000 feet). In Washington, Erysimum capitatum var. capitatum is found both east and west of the Cascades and in the Olympic Range; in Oregon it is found on both sides of the Cascades as well as westward through the Columbia River Gorge and into the Willamette Valley, and in the Siskiyous. See range map here. Several other varieties or subspecies are endemic to California; at least one (E. c. var. angustatum) is listed as endangered due to development, mining, agriculture, and invasive plants.
How it grows
Although western wallflower is technically a perennial plant, it’s often considered a biennial due to its short lifespan (rarely does it live past its second year). Like other short-lived perennials, it has a strong tendency to self-sow and is quite easy to grow from seed in pots or outdoor beds (but seeds reportedly have a short shelf life even when properly stored, so try to use them within a year or two).
Although wallflowers’ growth form and appearance vary (depending on location, light, soil, and moisture), here’s a general description: Deep green leaves — numerous, usually hairy, long and narrow — grow in a basal rosette, as well as along erect stems. Clusters of four-petalled, fragrant flowers are bright yellow to deep orange and appear at stem tips in a raceme. Bloom time is late April to July (depending on conditions and location); the resulting fruit is a one to four inch, upright, slender, flat seed pod called a ‘silique‘. In bloom, plants may reach one to three feet tall, with a spread of one-half to two feet.
Western wallflower plants are important food sources for wildlife, including the caterpillars of some lepidoptera (butterfly and moth) species, such as Sara’s Orangetip butterfly (Anthrocharis sara). Nocturnal moths and other butterflies, such as Painted Lady (Vanessa cardui), Anise swallowtail (Papilio zelicaon), Pale Tiger Swallowtail (Papilio eurymedon), and Persius Duskywing (Erynnis persius) are a few that may use the plant for nectar, as do some native bee and ant species. Mature seeds turn a deep orange and are eaten by — you guessed it — insects and birds who eat seeds.
Try it at home
Easy to grow and with a lengthy bloom period, western wallflower will brighten up any spot in full sun to light shade and looks particularly dazzling with a dark backdrop. Tolerant of drought since it typically occurs in dry, rocky, clay, or sandy locations, it needs well-drained soil to thrive, but will take artificial irrigation if drainage is adequate; additional moisture during dry months may even prolong its bloom time. Growing plants en masse, in clumps or drifts, will provide the most visual impact and support for wild ones, but they also look lovely interspersed with plants such as penstemon. Space plants about one to two feet apart.
As always, buy plants or seed propagated from source material that originated as close as possible to your site. Using such “local genotypes” helps ensure that you get plants that are well adapted to your area and preserves the genetic diversity that helps plants (and animals) adapt to changing conditions. Ask growers and nurseries about their sources if you’re unsure.