When plant species are introduced to new habitats, some don’t survive their new home, but some thrive.
And some take over. Those plants are known as invasive species.
“The main problem is that they compete with species that aren’t supposed to be there,” said Dan Salzer, senior scientist at the Nature Conservancy, an environmental conservation organization. “Things that were their predators back home aren’t here.”
Every invasive species has certain qualities in common. They adapt easily to new conditions and they prevent native species from reproducing, for instance.
They also impact every aspect of their environments, as they clog waterways, kill native species and damage existing agricultural systems. Getting rid of invasive species is extremely costly, which is why scientists would rather catch them sooner than later. Below are six invasive menaces to the Oregon environment:
Hedera Helix (native to northern Africa and western Asia)

This picturesque plant, peacefully hugging tree trunks and blanketing the forest floor, is actually slowly strangling both.
Commonly called English Ivy, this plant is a textbook example of an invasive species and the most widespread in the United States. It soaks up all the sunlight and destroys habitats for native species of plants and animals. Popular among landscapers and homeowners for aesthetic purposes, English Ivy doesn’t stay contained for long — it escapes into natural habitats and takes over. But it doesn’t spread all on its own.
“Birds eat the seeds, fly somewhere and excrete them,” said Kevin McWhirter, a volunteer coordinator for the No-Ivy League, a Portland based-organization that is taking action to save Forest Park and stop the spread of English Ivy.
The Oregon Department of Agriculture recently amended its Noxious Weed Quarantine law to ban the sale, transport and purchase of English Ivy.
Dreissena Polymorpha (native to Europe)

Also called Zebra Mussels, these plants first arrived in the U.S. in the early 1990s. They came over from Europe, attaching to large cargo ships. Now they cling to almost every submerged object they can find, including native mussel species. Removal is incredibly expensive, especially since the mussels coat every surface that is submerged — ships, pipes, rocks and docks. Some ships are required to pay a registration fee, and the money goes toward removal. The Zebra Mussel is so successful because it breeds rapidly and prevents native species from reproducing.
“The Zebra Mussel is a great poster species for getting people concerned about invasive species,” Salzer said.
Buddleja davidii (native to China)

Known for its tall stature and blooming purple flowers that attract butterflies all summer, this plant, called Butterfly Bush, is actually another plant the ODA has permanently banned from the market. It competes with native plant species and is considered one of Oregon’s worst invasive weeds. Butterfly Bush can be found in wetlands, natural forests and urban areas. Like English Ivy, it was originally used for aesthetic and landscaping purposes to attract butterflies. Unfortunately, the plant escapes personal confinement and infects natural habitats.
Sturnus vulgaris (native to Northern Africa, Southwest Asia, and Europe)

These invasive birds, called European Starling, are present on the University campus. The birds not only compete with other birds for food, but also out-compete numerous other land fauna. Economically, the birds cause huge damages for farmers because they descend upon the crops for food and nesting. On campus “they nest in cavities, are aggressive, and can take cavities away from our native birds,” said Peg Boulay, co-director of the Environmental Leadership Program at the University.
Apis mellifera scutellata (native to Europe and Africa)

The Africanized Honey Bee has made a huge negative impact on the beekeeping and honey industry. They take over nests of regular European bees, kill the queen and mate with the rest of the colony. Originally introduced to the U.S. in the 1950s, the African bee was supposed to mate with the European bee to create a better honey-producing hybrid. Instead, a species of bee was born that produced much less honey than its European counterpart and is hundreds of times more aggressive. As a result, the beekeeping industry is scrambling to produce more honey and re-queen the original populations of bees. The Africanized bee will chase an intruder up to a quarter mile away, stinging multiple times. This is where the nickname “killer bees” comes from. Though they are more common in southwestern states, there have been reports of the bees moving north to Oregon.
Polygonum cuspidatum

The Japanese Knotweed is an incredibly horrific invasive plant to areas of Oregon. Like English Ivy, the spreads quickly and thickly, blanketing the forest floor and stealing sunlight from native plants. It makes a monoculture out of its environment and brings down biodiversity. Currently, the Nature Conservancy is working to save the Sandy and Clackamas Rivers, and Salzer thinks they’ve caught the outbreak early enough to treat it efficiently and cost-effectively. However, this noxious plant has already taken over the banks of the Nehalem River, which Salzer said is a lost cause.
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