We have plenty of thistles growing in our area and landowners across the region are working hard to combat these prickly invaders. While most of the thistles growing in our area are invasive, some of them are actually native. Unfortunately, a recent discovery from eastern Oregon marks the addition of a new invasive thistle to […]
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, […]
Distinctive orange-margined sepals of the Garden loosestrife
Garden loosestrife infestation
Garden loosestrife being controlled by staff from the Oregon Dept. of Agriculture
Common names:
Garden loosestrife, garden yellow loosestrife,
Scientific Name:
Lysimachia vulgaris
Description:
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.
Yellow 5- petaled flower, that lack reddish or black streaks or dots
Bloom time:
Typically blooms during July and August.
Look-a-likes:
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.
Habitat:
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.
Impacts:
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.
This past season we have seen a rise in the number of Oblong spurge (Euphorbia oblongata) sites appearing in Clackamas County. Oblong spurge is a class A noxious weed in the state of Oregon, and eradication of this species is required across the state. It is known to be highly aggressive and can displace native […]