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 […]
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The Thorn in Our Side Himalayan blackberry (Rubus bifrons) 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 wide-spread and aggressive weed is native to Armenia and Northern Iran. It is considered an invasive species in many parts of […]
Do you think you’ve found a noxious weed? Here is how you can get help to identify and report your find! One of the most important aspects in controlling invasive weeds is to verify the identification if invasive weeds before you work to control them. Knowing the difference between an aggressive weed and a common […]
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 […]
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 […]
Policeman’s helmet (Impatiens glandulifera) is an invasive weed which grows in ditches, wetlands, and along waterways. Native to India, this fast-growing annual was introduced as a ornamental plant due to its impressive growth and the showy purple, pink or white blooms. Since introduction, it has escaped cultivation to become the dominate riparian vegetation in many […]
Orange hawkweed (Hieracium aurantiacum) is a relatively new invasive weed in Clackamas County. With your help, our team plans 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 gravel pits, roadsides, meadows, pastures, […]
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 priority invasive weed on your property. Sometimes referred to as Jack-by-the-hedge, garlic mustard is easily identified […]
Garden loosestrife (Lysimachia vulgaris) is one of the most recent additions to Oregon’s noxious weed list. As a class A noxious weed, the goal of land managers is to rapidly control infestations before they have a chance to gains a foothold. One critical component of this is approach is to increase awareness of this new […]
Garden loosestrife, garden yellow loosestrife,
Garden loosestrife is a tall upright rhizomatous noxious weed that grows up to 5 feet in height. It is characterized by terminal panicles of bright yellow 5-petaled flowers. Leaves are opposite to whorled, nearly sessile and lanceolate 7-12 cm in length. The stems and leaves are soft and hairy. Flowered are ringed by distinctive orange-margined green sepals. Underground rhizomes can spread to lengths up to 15 feet. Plants reproduce from both rhizomes and seeds.
Height of mature plants
3 to 6 feet
Yellow 5- petaled flower, that lack reddish or black streaks or dots
Typically blooms during July and August.
The closely related Yellow loosestrife (Lysimachia punctata) is a less aggressive garden ornamental, with lower flowers from emerging from the leaf axils, and the yellow flowers lack the orange-margined sepals, characteristic of the noxious garden loosestrife.
Garden loosestrife is found escaping in wetlands and along streams and river. It is also likely to be found in garden setting. This species is known to occur in only one location in Oregon.
Garden loosestrife invades wetland and riparian areas, where it displaces desirable native vegetation. Once established it can spread rapidly, and has been known to displace very hearty plants such as cattails. Invasion by garden loosestrife disrupts habitat for fish and wildlife, and can limit recreation opportunities in highly invaded sites.
Noxious Weed Listing:
- WeedWise: Priority
- State of Oregon: Class A,T
- State of Washington: Class B
- Four County CWMA: A
- Columbia Gorge CWMA: A
This species is native to Europe.
Present in Clackamas County: