During the blooming season people often send me photos of plants they’ve found and can’t identify. A few days ago I received a photo of a plant I’d never seen before. It’s not in my book, Wildflowers of the Pacific Northwest, nor in the Washington Wildflowers smartphone app. But I instantly recognized the genus, Orobanche. There aren’t many species in the Pacific Northwest and they’re rather distinctive.
My correspondent, Jeremy, said he’d found it at Deception Pass State Park, which narrowed down the choices when I looked up the broomrapes in Vascular Plants of the Pacific Northwest and looked at photos in the University of Washington Herbarium online image collection. It seemed likely the plant was California broomrape, Orobanche californica.
Since I’d never seen it, I asked Jeremy if he could pull the GPS coordinates from the smartphone photo he’d sent and he quickly obliged. Deception Pass is less than an hour from Bellingham, so I hopped in my truck and headed down the road. It was only about a ¾ mile walk from the parking lot to the location. Jeremy had told me he found two clumps of the plant growing among dry grasses on the edge of a cliff. When I got close I slowed down and scanned the ground for the little clump or purplish flowers, no bigger than a child’s fist. It was right where he described and there were still fresh blossoms so I went to work photographing it. I spent more than half an hour working with this one specimen.
California broomrape isn’t officially rare, but neither is it particularly common. Despite being named for California, it grows all along the west coast from California north to British Columbia. Like other members of the genus, Orobanche californica is a parasite. It has no chlorophyll and no leaves. Technically, it’s a mycoheterotroph, meaning that fungi in the soil play a role in connecting the roots of the broomrape to a host plant from which it derives its nutrients. According to PNW Plant Disease Management Handbook, California broomrape’s host plant is gumweed. That explains why this broomrape is usually found near the coast where gumweed is common.
While California broomrape doesn’t make it’s own food, it is a seed-bearing flowering plant. The short flower stems are covered in sticky glands that glisten in the sunlight. Many stems grow crowded close together, forming a dense clump like the one I photographed.
California broomrape is a plant you aren’t likely to be able to grow in your garden. The special relationship it has with a host plant is very difficult to reproduce in cultivation. Just stay alert when you’re out hiking in the coastal habitat where it grows and you might be lucky enough to spy it. Then get down on the ground to enjoy it up close.
About that common name, broomrape. In the Old World a species of Orobanche is parasitic on a shrub called broom (Cytissus) and perhaps the parasite resembled the vegetable, rape, which is related to broccoli, cabbage, and mustard. Some species of Orobanche in Europe and Asia can be quite destructive to crops.
A more common broomrape in the Northwest is Orobanche uniflora, naked broomrape. My friend Tanya Harvey wrote about it earlier this spring in Attack of the Orobanche. You’ll also find more information about it on my PNW Flowers website.