Lawnweed, Field Burweed
General: Carpet Burweed is a broadleaf winter annual that spreads easily to form a dense groundcover.
Flowers: Are inconspicuous and small. They are yellow-green and disk-like. Their greenish flower heads grow in the basal rosette of the leaves.
Stems: Are hairy. Rosettes are 3 – 5 cm wide and 7 cm tall, with stems arranged in a sprawling pattern. Each plant has up to 10 stems growing from its base.
Leaves: Are alternate, slightly hairy, and feathery in shape. The leaves are also described as carrot or fern-like.
Seeds: Are ovate and flattened with a thick spine. Individual seeds are 2.5 – 3.5 mm long, and are grouped (up to 10) in sunflower-like seed heads.
Wild Carrot, also know as Queen Anne’s Lace (Daucus carota), grows in a similar habitat and has a similar leaf structure. Unlike Carpet Burweed, this plant’s stems can grow up to 1 meter tall.
Pineapple Weed (Matricaria discoidea) also grows in a similar habitat and has a similar leaf structure. Unlike Carpet Burweed, the larger flowers smell like pineapple when crushed.
Habitat and Origin
Carpet Burweed is native to South America. Its first confirmed sighting in Canada was in Ruckle Park on Salt Spring Island, BC, in 1996.
Carpet Burweed prefers open, grassy areas with disturbed, compact soils and full sun exposure. Most vulnerable for spread are areas that are wet in winter, and dry and trampled in summer. Carpet Burweed is commonly found in lawns, playing fields, golf courses, paths, and other disturbed, well-trodden areas.
Propagation & Vectors of Spread
Carpet Burweed is a winter annual that reproduces by seed. Its bur-like seeds are well adapted for short-distance transport on the bottom of animal paws and hoofs, soft-soled shoes, and other soft materials such as tents and tires. A seed’s spine, once attached, will break off, allowing the seed to be transported only a few meters.
Carpet Burweed can also spread through the movement of soil that has been contaminated with its seeds.
Ecological, Economic, & Health Impacts
- Creates a dense, carpet-like groundcover that prevents the growth of native species.
- Reduces biodiversity.
- Out-competes tended grasses and leaves behind wide, brown patches which are unsightly.
- The spiny seeds are painful for animals and humans to walk on.
What Can I Do?
Carpet Burweed is NOT currently found in the Sea to Sky region. PREVENTION and EDUCATION are important to keep this species from establishing.
Learn to identify Carpet Burweed: use the images presented in this profile page to learn how to identify Carpet Burweed.
What to do if you spot it: You can report any Carpet Burweed sightings by clicking here.
- Regularly monitor properties for weed infestations.
- Minimize soil disturbances and promptly revegetate disturbed areas to prevent the growth of Carpet Burweed.
- Ensure all flowering heads or buds are bagged or covered to prevent spread during transport to designated disposal sites.
- Unload, park or store equipment or vehicles in infested areas; remove plant material from any equipment, vehicles or clothing used in such areas and wash equipment and vehicles at designated cleaning sites before leaving infested areas.
- Plant Blueweed in a garden, no matter how well-contained its enclosure may seem.
- Compost any flowering heads or buds. Instead, dispose of Carpet Burweed in the general/household waste stream at the landfill as the seeds may persist the composting process.
- Move soil, gravel, or fill that has been contaminated with Carpet Burweed.
- Small infestations of Carpet Burweed may be effectively controlled by hand-pulling, but this must be done before the seeds set.
- Ensure that any flowering heads or buds are bagged to prevent unwanted spread.
- For large infestations, flaming has been found to be the most effective method of removal, though it is often impractical.
- Mowing is ineffective due to the low-lying nature of the plant.
- Herbicides such as clopyralid, picloram and triclopyr can be effective in removing this weed, however resistance has been reported. Moreover, picloram is not suitable for wet, coastal soils.
- Successive chemical treatments using alternating, selective classes of herbicides is recommended.
We recommend that any herbicide application is carried out by a person holding a valid BC Pesticide Applicator Certificate. Before selecting and applying herbicides, you must review and follow herbicide labels and application rates; municipal, regional, provincial and federal laws and regulations; species specific treatment recommendations, and site-specific goals and objectives.
Maintaining healthy, well-fertilized turf areas can prevent the establishment of Carpet Burweed.
There is no biocontrol available for this plant.
- BC Parks, Best Management Practices for Invasive Plants in Parks and Protected Areas of British Columbia, https://bcinvasives.ca/wp-content/uploads/2021/01/ISCBC-BC-Parks-BMP-180412-WEB.pdf
- Coastal Invasive Species Committee, Carpet Burweed, https://www.coastalisc.com/carpet-burweed/
- Fraser Valley Invasive Species Society, Carpet Burweed, https://fviss.ca/invasive-plant/carpet-burweed
- Gary Oak Ecosystem Recovery Team, Carpet Burweed, https://goert.ca/wp/wp-content/uploads/IS-factsheet-soliva-sessilis.pdfhttps://www.goert.ca/documents/S.sessilis.pdf
- Invasive Species Compendium, Soliva sessilis, https://www.cabi.org/isc/datasheet/108899#tosummaryOfInvasiveness