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Class B Noxious Weed

Lawnweed
Soliva sessilis
 

lawnweed

Other common names: field burweed
 Plant family: Asteraceae (Compositae)
Year listed:
Native to: South America

Why is it a noxious weed?

Lawnweed establishes in high-use recreational areas - public swim and boat launching areas and sites that have a high level of disturbance in managed grass areas. This weed produces very sharp seeds (burs) that can puncture skin and attach themselves to tires. This winter annual successfully out-competes the perennial grasses of managed lawn areas in parks and recreation areas world-wide. Lawnweed dies back in the summer leaving open, brown and bare areas, which contribute to its spread.

How would I identify it?
General Description: Lawnweed is a low growing winter annual. The plant will grow to about two inches tall, with a spread of six inches in diameter.

Leaves:

  • pinnate
  • feathery appearance

Flowers:

  • small
  • composite
  • greenish, translucent discs, no rays

Stems:

  • 1-10 stems
  • hairy or sparsley hairy
  • often have purple spots

How does it reproduce?
Lawnweed reproduces by seed.

Where does it grow?

Lawnweed is found in managed perennial grass areas usually associated with heavy foot traffic, public swim areas, and boat launches of public lakes.This plant is also found in watered lawns, golf courses, and hard-packed soils near paths and roadsides.

What is the distribution in Washington State?
 
  • Lawnweed was first identified in 1991 in Snohomish County at the Flowing Lake County Park. Lewis County first identified lawnweed in 1994, at Ike Kinswa State Park.
  • If you think you may have seen this weed, please contact your county weed coordinator or us at noxiousweeds@agr.wa.gov.

 

  • Distribution map not available at this time.

How do I control it?

General control methods:

Cultural: Information not available at this time.

Herbicide: Please refer to the PNW Weed Management Handbook, or contact your county noxious weed coordinator.

Mechanical: Information not available at this time.

Biological: None known.

For more information
For more information, download our Written Findings.

 

More Photos-Click photo to enlarge
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Mat of lawnweed, car key as size reference.

 Last updated July 02, 2008