Experts at the Oregon Department of Agriculture say that once land is invaded by medusahead, it becomes largely worthless, incapable of supporting native animals, birds or livestock.
The sharp and twisting points on the tips of medusahead injure the eyes and mouths of animals, and give the plant its name - based on the female monster in Greek mythology that had hair composed of writhing snakes. The plant takes up other soil resources and its deep root system soaks up limited moisture. It creates fuel for wildfires, has a high silicon content that wears away the teeth of animals, is virtually inedible, and it prevents many other plants from germinating.
"Annual grass invasion is driving one of the largest changes in vegetation structure ever documented," the researchers wrote in their new study. "This conversion has major negative impacts on ecosystem function, wildlife and fire regimes.
"We expect that medusahead will continue to invade both native perennial and less-undesirable invasive annual grasslands, because of its higher relative growth rate and extended period of growth," they reported.
Medusahead is not a new problem, only a rapidly worsening one. Native to the Mediterranean region, it was imported to the United States in the late 1880s and has gradually established footholds since then.
It's now found on about 2.5 million acres in the U.S. much less than other invading species such as cheatgrass but it's widespread in the Pacific Northwest and most of Oregon, including the Willamette Valley. Its impact on ecosystems when established is far greater than some other species, experts say, and it has evolved many traits that allow it to invade North America.
"For too long we've treated these invasive species as something you just mow, spray with herbicides, or chop out somehow, and then forget about them," Mangla said. "That just treats the s
|Contact: Seema Mangla|
Oregon State University