Himalayan blackberry (Rubus armeniacus, formerly Rubus discolor and Rubus
procerus) is a European shrub that was introduced in the United States as a crop in the late 19th century. It escaped cultivation and has since invaded a variety of sites, including low-elevation streamside areas throughout
the Pacific Northwest. Listed as...
Gorse is a spiny, evergreen shrub native to the Mediterranean region. It was introduced on the West Coast of the United States as an ornamental in the late 1800s. Gorse was first found in Oregon in Benton County in 1916. Gorse infestations are concentrated along the Oregon coast, particularly south...
Japanese and giant knotweeds were introduced to North
America in the late 1800s as ornamentals but soon escaped into
the wild. They are particularly invasive along streams, roadsides, and
waste areas. Large, spreading patches of knotweed can completely
dominate and displace native species in open sunlight. Erosion
can increase on...
Knapweeds are a serious problem in Oregon because they vigorously
invade disturbed or degraded sites and form dense populations that exclude native and desirable plant communities, causing economic and
ecological losses. Their ability to spread rapidly by seeds and
roots makes control very difficult. Seeds can remain viable for 5...
Slender false-brome is a perennial grass species native
to Europe, Asia, and North Africa. The species has
exceptionally wide distribution, occupying forested and open
areas at a variety of aspects and elevations. Populations are known
in riparian forests as well as in upland hardwood and conifer forests
under patchy and...
Himalayan blackberry, also known as Armenian blackberry, is a widespread invasive species in western Oregon and also grows in some eastern Oregon riparian zones. Commonly found in riparian areas, it also
grows along roadsides and fence corridors and in open woodlands,
logged areas, and other disturbed sites. It grows best...
Yellow starthistle (Centaurea solstitialis L.) is an introduced Asteraceae
that has become established on 10 million acres in the Pacific Northwest and
California. This weed functions as an annual or short-lived perennial and depends
on seeds for reproduction. Strategies of control that reduce plant fitness or lower
seed production or...
Yellow starthistle, a native of the Mediterranean
region, arrived in this country in 1869 as a
contaminant in alfalfa seed. It is a strong invader of
disturbed areas, rangelands, and roadsides and thrives
in areas of summer drought. A yellow starthistle invasion will
reduce biodiversity by choking out native plants....
English ivy is a trailing or climbing vine in the
ginseng family, native to Europe and brought
to America by early colonists. It is commonly cultivated as a
groundcover and is widespread in the Pacific Northwest, where
it has invaded many wild and unmanaged areas. It is an aggressive