English holly (Ilex aquifolium) is a popular evergreen frequently noticed during the month of December when festive decorators “deck the halls with boughs of holly”. For many people, the shiny, dark green leaves and red berries of holly are synonymous with the holiday season. This popular plant, however, is not native to Oregon. In fact, […]
The Scourge of Spurge Laurel Spurge laurel (Daphne laureola) is neither a spurge nor a laurel, but rather an invasive plant in the Daphne family. This perennial plant has poisonous berries, spreads aggressively in our native forests, and is increasingly being found in Clackamas County. Native to Europe, spurge laurel was introduced in Oregon as […]
The Thorn in Our Side Himalayan blackberry (Rubus armeniacus) tantalizes us with its sweet fruits in the summer and tortures us with its prickly vines all year long. Also known as Armenian Blackberry, this widespread and aggressive weed is native to Armenia and Northern Iran. It is considered an invasive species in many parts of […]
September is the Time to Control Japanese Knotweed Japanese knotweed (Fallopia japonica) has been called a “nightmare” and a “botanical bully,” and is one of the 100 worst global invaders. These characterizations give you a pretty good idea of just how unwelcome this invasive weed is in our community. Japanese knotweed is fast-growing and hardy, […]
Puncturevine (Tribulus terrestris) is aptly named! This invasive weed has spiny seed heads that can easily puncture a bike tire, inflatable raft, animal paw, or footwear. Be on the lookout because it is beginning to make its way into Clackamas County from eastern and southern Oregon. Also known as “goathead”, puncturevine is native to southern […]
Tansy ragwort (Senecio jacobaea) is an invasive weed with a long and deadly history in the Pacific Northwest. In Oregon, it is designated as a Class B invasive weed. It is believed to have been introduced here in the early 1900s through ballast water from a ship. This plant is native to Europe and Asia […]
Policeman’s helmet (Impatiens glandulifera) is an invasive weed that grows in ditches, wetlands, and along waterways. Native to India, this fast-growing annual was introduced as an ornamental plant due to its impressive growth and the showy purple, pink, or white blooms. Since introduction, it has escaped cultivation to become the dominant riparian vegetation in many […]
Orange hawkweed (Hieracium aurantiacum) is a relatively new invasive weed in Clackamas County and we are working to keep it from becoming a common problem for landowners! A member of the sunflower family, orange hawkweed is native to central and southern Europe and grows in open areas like roadsides, meadows, pastures, hayfields, and disturbed sites. […]
Garlic mustard (Alliaria petiolata) is an increasingly invasive weed in our community. Native to central and western Europe, this fast-growing plant commonly invades sites such as parks, trails, roadsides, and streamsides. April is a great time to manage this important invasive weed on your property. Sometimes referred to as Jack-by-the-hedge, garlic mustard is easily identified […]
Canada thistle (Cirsium arvense) is a widespread invasive weed found in all parts of Clackamas County. Unlike the many native thistles found in Oregon, Canada thistle can quickly overrun an area and displace native plants, reduce agricultural yield, and create problems for grazing animals when they infest a field or pasture. They also cost a […]
