Trouble in Paradise—Invasive Plants
by Debbie Teashon
Weherhauser building covered in ivy.
Spirea 'Gold Flame' is an attractive alternative.
I observe ivy (Hedera helix)—a serious pest in the Pacific Northwest—growing on trees in many locations in Washington, Oregon and British Columbia. Until I walked through Fort Ward State Park on Bainbridge Island, Washington,I didn’t realize the full impact this species has on our forests. In this park, the ivy has invaded a large portion of forested areas. The plant grows up the trees or along the ground; everything in its path is smothered in the glossy telltale leaves of ivy. It has destroyed the diversity of the native plant life on the forest floor. All that remains is this mono-crop vine that will soon destroy the trees. After seeing the carnage, imagine my surprise when I saw the Weyerhaeuser building in Federal Way, Washington, purposely planted with ivy, the very plant that threatens the forests that their business depends on!
In May, when our northwest native Rhododendron macrophyllum is in bloom, I love driving through Whidbey Island or around the Kitsap Peninsula, spotting this native species in full bloom. On a coastal trail near Florence, Oregon, I went for a hike just to see these Rhododendrons flowering in great numbers along the trail. Near where I live, I have noticed the invasive scotch broom (Cytisus scoparius), with its electric-orange flowers, blooms at the same time the Rhododendrons open their flowers. The scotch broom’s color overpowers and clashes with the trusses of soft pink Rhododendrons flowers. Besides the scotch broom's unappealing appearance, it reseeds itself prolifically and overwhelms most native plants.
These are just a few examples of plants gone wild in our region. A smorgasbord of exotic and native plant species are available to gardeners from nurseries, but only a handful of plants are invasive. As gardeners, it behooves us to avoid planting species that have a tendency to take over our gardens as well as our natural areas. Already too many of them have escaped from the exotic plant genie bottle, and we are paying the price!
With so many alternative plants to choose from, we can avoid planting invasive species that add to the problem. For example, instead of the rangy and very invasive butterfly bush—(Buddleia davidii), choose Spireas as an attractive alternative. A Spirea will also feed the butterflies and add beauty to our landscapes without causing harm to the environment.