The Yellow Arbor Lupine

Updated: 3 days ago


Now that this coronavirus catastrophe is interrupting my Wednesday routine of volunteering at Sutro Stewards Nursery, I have more time to weed, groom and appreciate my own backyard gardens.

My past blog posts were all about the bird life that I found on Mount Sutro, from the Black Phoebe showing off in the Rotary Meadow to the Red-shouldered Hawk screaming and displaying in the skies above. I am taking this opportunity, with the stay at home orders, to write about a topic that has been my pastime for years, backyard gardening.

My neighborhood, the Inner Sunset, is just north of the UCSF Parnassus campus. During the decades that I have lived here, I have christened the adjoining backyards the “Fourth Avenue Flyway”, as I see birds fly overhead from the vicinity of the UCSF Mount Sutro Open Space to the Golden Gate Park and points north. Focusing on the fact that birds require shelter (vegetation) food (native plants providing berries and accompanying insects) and water, I have taken steps to accommodate.

With an eye towards biodiversity, my plant selections took a turn about twenty-five years ago. To my surprise, at the San Francisco Botanical Garden sales I found California-Native plants. One by one, I purchased California-Native native plants in order to introduce a community of plants, insects and the birds that depend upon them to my garden. In recent years I have purchased “locally native” plants, a more narrow definition, from the Sutro Stewards Nursery.

Right now, during May and June, the Coastal bush lupine, otherwise known as the Yellow bush lupine (Lupinus arboreus) is blooming. This is a large, perennial shrub that is often seen in sandy areas near the ocean strand. Blowing sands have moved shifting sand dunes on the west side of town for millennium, a region named “the

Outerlands.” Now houses and fences block the sea breezes. Retaining walls create modified environments.

Plants adapted to sand do well in this neighborhood. Over time, leaf litter has added humus to the earth, increasing its water retention traits. The deep shade to the north of the retaining wall favors different plants than the sand on the opposite side of the yard that bakes in the afternoon sun.

The Coastal bush lupine blooms in full sun. Right now it is bursting with spikes of yellow lupine flowers and palmate-leaved vegetation. The burst of glorious color in yellow spires of flowers among the flush of green vegetation can be breathtaking, particularly when the sun breaks through the fog.

Having become familiar with lupine in my garden over the years, I now know that this is not the time to passively admire the blossoms. Early in May, close inspection reveals two infestations of insects on my two distantly located lupines. These infestations can sap the vigor of the plant, resulting in withered flowers and leaves. (Why birds don’t come and devour these insects is beyond my ken.) Plump aphids line the flower spike and are tucked among the blossoms. The flowers are obviously suffering, not developing normally, looking thin and starved. With my fingers I stroke the flower spike, smashing thousands of plump aphids at a stroke. Over the course of seven days of such intervention, the shrub recovers partially, flower buds plump up again and blossoms burst forth. (Analogies to the current human infection are rife.)

On the other Yellow arbor lupine shrub many branches are withering. Now I know that aggressive action is warranted and I look for an infestation. Sure enough, upon close inspection I find a one half inch long insect that runs for cover among the buds. To hunt these particular critters is like chasing a shadow! I shake them out and catch them in a jar. Doing this as often as possible I am hoping to prevent the destruction that has occurred from this pest in the past, a destruction that overwhelmed leaf and flower. A few years ago I brought a specimen to the horticulturist at the San Francisco Botanical Garden who identified this insect as a pest. I have forgotten its name, but recognize its behavior and body design. Now wiser, I don’t solely rely upon birds to find and eat this pest. Rather, as often as possible, daily, I hunt for this pest, removing them. The buds and vegetation will acquire vigor again.

During May and June I see several varieties of bees tending to the lupine flowers, pushing down the lower pair of petals in their hunt for food, meanwhile acting as pollinators. Spiders and small flying creatures live among the leaves. White-crowned Sparrows typically live in habitat dominated by the Yellow arbor lupine, though none reside in my yard. For the next several months the green, developing lupine seed pods will attract Lesser Goldfinches. In autumn, the dry opened seed pods will attract Chestnut-backed Chickadees who will dangle as they search for food within.

The Yellow bush lupine is listed in Calflora as a native that can become invasive. However, as this plant does not have thorns, I welcome it. I am willing to do the maintenance, to pull seedlings and to prune back the lupine so that this plant can thrive within the confines of a backyard sandlot. It attracts bugs, birds and the human gaze.

If we select and maintain increasing percentages of locally native plants, we promote biodiversity here among our adjoining backyards, along the Pacific Flyway.

The song of a white crowned sparrow.

References:

Calflora


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Sutro Stewards is a project of the San Francisco Parks Alliance, a 501(c)3 California nonprofit public benefit corporation.