What is the species?
- Aegopodium podagraria (goutweed)
Goutweed is a species of concern known for filling in garden spaces and for being very hard to control. Its sale is prohibited in several New England states, and has been noted as invasive in throughout the East Coast, the Midwest and Pacific Northwest.
Why are we concerned?
Goutweed is known to form dense patches of perennial plants. Its resistance to management increases concerns, as well. Goutweed infestations may lead to:
- Reduced plant diversity as other species are displaced
- Increased costs in management of natural areas
How does it spread?
Goutweed is thought to spread primarily by root expansion but may also be able to spread by seed. It is well-known in landscaping, and variegated [white-edged] specimens are common. Goutweed seeds are moved by:
- Hiking boots
- Running water
What does it look like?
Goutweed creates a low cover of leaves composed of generally three leaflets. Lower leaflets often have a mitten shape. Landscape varieties often have white on the edges of leaves, though these varieties may revert to all-green leaves.
Are there any lookalikes?
Goutweed looks vaguely like many of the herbaceous species found under forest canopy in the Pacific Northwest. Sweet cicely (Osmorhiza chilensis) has similar foliage and Pacific waterleaf (Hydrophyllum tenuipes) forms similar groundcover. Goutweed flowers, however, are in larger clusters than sweet cicely, while goutweed leaves are obviously three-part, as opposed to waterleaf or many other lookalikes.
How do we deal with it?
- Manual: Digging up goutweed is moderately effective but requires persistence and regular monitoring. Manual management is only recommended on small patches. Excavated soil and bulbs should be go in the trash, not in compost or yard debris.
- Herbicide: Herbicide trials in thePortlandarea are ongoing. Spring treatments have not been as effective as claimed; fall treatment may give better results. On patches of more than a few plants, herbicides are used in combination with the manual methods described above.
- How can folks help?
Goutweed is not a species that the city is currently managing. Private property holders are, however, strongly encouraged to manage and properly dispose of goutweed.