by Marilee Henry
Take a hike this spring/early summer through moist western Washington meadows or locally, stroll through Seattle's Discovery Park and surround yourself in spectacular swaths of fragrant purple-blue bigleaf lupines!
As a group lupines are probably the most readily recognized native flowers in our state. With over 20 species in Washington, they occur in a wide variety of habitats from sea level to alpine elevations. The genus Lupinus is a most valuable one, hosting larvae of 64 different species of butterflies and moths, which are essential foods for birds in raising their young. These plants are also critical nectar and pollen sources for bumblebees, bees, flies, beetles, wasps, butterflies, and hummingbirds.
As members of the pea family, lupines have special root nodules containing bacteria that convert atmospheric nitrogen to compounds that are then available for uptake by plants. This characteristic makes them tolerant of poor soils and useful for nutrient enhancement of damaged areas. Lupines were among the first native plants to reseed themselves in burned lands after the eruption of Mt. St. Helens. Their strong roots also aid in the breakup of compacted soils.
Bigleaf lupine, this month's featured species, and the largest of our native lupines, grows to 4 or 5 feet in height. Its large palmately-compound leaves can reach 6 inches in width with 10 to 17 leaflets forming lush disks on erect stems. Dense flower spikes up to 20 inches tall of pea-like blossoms bloom May to June in lowland regions, slightly later at higher elevations. Colors range mostly in blues to violets with pink and white hues commonly present. Hybridization with the tree lupine L. arboreus, a California native considered invasive in Washington, has produced many garden (non-native) varieties of lupines with widely ranging colors.
Full morning sun locations that are moist in spring but afford good drainage are preferred for bigleaf lupine. Hot afternoon sun may wilt leaves, and heavy wet soils can cause powdery mildew. Though classified as a perennial, individual plants usually do not last more than five years. To maintain a permanent bed, reseeding is necessary. Fortunately, this species readily seeds itself and will spread into swaths unless seed pods are removed before popping open at maturity. Lupines do not transplant well, so care must be taken to minimize root disturbance when attempting it. Direct seeding is the most successful propagation technique.
Native lupines of North America contain alkaloids that cause a bitter taste and are toxic if eaten by animals or humans. They should not be planted where grazing cattle, horses, goats, etc., could ingest them (deer are sensible enough to avoid them) or where their seeds could be flung into nearby pastures. However, several annual species of "sweet" lupine native to the Mediterranean region contain about 25% the concentration of these alkaloids and are grown for both human and livestock consumption. Their seeds can be ground into a high-protein flour that is increasingly being used in meat substitutes and bakery goods, particularly gluten-free products. People with peanut allergies should avoid foods containing lupine products - another reason to carefully read those ingredient lists!
Bigleaf lupine has gotten a bad rap as an invasive outside of its native range. For example, in areas around the Great Lakes and eastern states it has been introduced and said to be out-competing L. perennis, the sole host plant for the endangered Karner Blue butterfly. This is the very reason why one should landscape with locally native species over exotics. Any plant taken outside its native range has the potential to disrupt the ecology where it is introduced.
Luckily for us, this spectacular spring bloomer is one of our local natives that belongs in PNW urban gardens, attracting many pollinators with its gorgeous displays.
Remember, "You are nature's best hope!" - Doug Tallamy.
Marilee Henry
Kirkland Community Wildlife Habitat Team Member, Washington Native Plant Society (WNPS) Native Plant Steward, Green Kirkland Steward, Finn Hill Neighborhood Alliance Contributor