Goutweed (Aegopodium podagraria)
Goutweed is an herbaceous perennial plant native to Europe and northern Asia. It was first brought to North America during the early stages of European settlement as an ornamental garden plant, and is commonly used as groundcover1. Today, it is a problematic invasive species that is commonly found in moist forests, ravine systems, and along water courses. Goutweed is commonly found in urban areas, escaping into natural ecosystems within the Credit River Watershed.
Goutweed spreads via underground rhizomes, tolerating full sun to partial shade, and a variety of moisture conditions. Its leaves are basal, and are divided into three groups of three leaflets. The leaflets are toothed and sometimes irregularly lobed or divided. The natural plant is a light green colour, but the variegated form has bluish green leaves with white edges, and is more commonly sold in garden centres1.
Goutweed with green leaves
Goutweed blooms between May and June, producing tiny white flowers arranged in flat topped clusters, called compound umbels, which are held above the foliage on leafy stems (which look similar to Queen Anne’s Lace)2. Goutweed seeds produced require recently disturbed soil and a sunny location to survive after germination. For this reason, Goutweed does not have much success reproducing by seed in forest ecosystems. However, even one established plant can create a large colony by spreading through its aggressive rhizomes3.
As an invasive species, Goutweed forms dense patches that displace native plants in the ground layer of an ecosystem2. The primary cause of its spread over long distances is human activity in the form of intentional plantings, and the dumping of yard waste containing goutweed rhizomes.
Because it has limited reproductive success by seed, small patches of Goutweed can be easily controlled by digging up the plant (with careful attention given to removing the entire rhizome) or covering with a tarp or weed barrier for at least one growing season3. Plants dug up with intact rhizomes should be dried in the sun for several days to ensure they are dead, so that they will not be able to resprout if they come in contact with a suitable substrate3. Therefore, if you are removing Goutweed from your garden, do not put it in your compost. Chemical control is also an effective method for large infestations.
For more information on Goutweed, please contact CVC via email or to report sightings of Goutweed call the Ontario Federation for Anglers and Hunters Invasive Species Hotline at 1-800-563-7711 and add the sighting to the EDDMaps Ontario website.
- Small, E. 1973. Photosynthetic ecology of normal and variegated Aegopodium podagraria. Canadian Journal of Botany 51: 1589-1592. Web. 15 August 2018. http://www.nrcresearchpress.com/doi/pdf/10.1139/b73-202
- Evergreen. “Invasive Plant Profile: Goutweed, Bishop’s Weed: Aegopodium podagraria.” Web. 15 August 2018. https://www.evergreen.ca/downloads/pdfs/Invasive-Plant-Profile-Goutweed.pdf
- Garske, S. and D. Schimpf. 2005. “Fact Sheet: Goutweed”. Plant Conservation Alliance’s Alien Plant Working Group. Web. 15 August 2018. https://www.invasive.org/weedcd/pdfs/wgw/goutweed.pdf