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Class C Noxious Weed

Common Groundsel
Senecio vulgaris
 

Image of common groundsel

Image courtesy of Ben Legler

Other common names: Old-man-in-the-Spring
Plant family: Asteraceae
Year listed: 2004
Native to: Europe and North Africa

Why is it a noxious weed?

Groundsel is a problem in forage crops because it is toxic to livestock.

How would I identify it?
General Description: The plant usually is a winter annual, sometimes biennial, though it may germinate in all seasons. It grows from 4 to 18 inches tall.

Leaves:

  • Deeply lobed with toothed margins and may be smooth to hairy or woolly.

  • Little or no leaf stalk, and are arranged along the stem in a spiral.

  • Basal leaves usually are purplish on the under surface, 1 to 4 inches long, and 1/2 to 1 1/2 inches wide.

 Flowers:

  • Flower heads are numerous, with yellow disk flowers, but no ray flowers.
  • The heads are cylindrical, 1/4 to 1/2 inch long, with black-tipped bracts around the base.
  • The seeds are slender, ridged, about 1/2 inch long, and tipped with a tuft of silky white hairs.

Stems:

  • Hollow and rather succulent.

How does it reproduce?
Groundsel produces abundant seeds, which spread by floating on the wind with their parachutes of hairs. One groundsel plant can produce as many as one million seeds in a season.

Where does it grow?
This weed is found in many crops, including forages, cereals, mint, berries, and row crops, as well as in ornamentals and vegetable gardens.

What is the distribution in Washington State?

How do I control it?

General control methods:

Cultural:  Cultivation kills groundsel plants, and if done prior to seed formation is an effective control method.

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

Mechanical: Common groundsel can be controlled by tillage in the fall and early spring. New plants, however, coming either from the reservoir of seeds in the soil or from seeds blown in from adjacent areas, will establish readily in newly-cultivated soil.

Biological: Larvae of the cinnabar moth, Tyria jacobaeae, an insect released extensively in western Oregon and western Washington for biological control of tansy ragwort, also eat groundsel. These caterpillars are not capable of significantly reducing a groundsel infestation, however, because they are present only from June through August.

Are there plants that may be confused with (name of weed)?

A similar species is woodland groundsel (Senecio sylvaticus). This plant generally is larger, growing up to 3 1/2 feet tall, with leaves more deeply lobed than those of common groundsel. Leaves are greenish gray and woolly. They are largest near the base of the plant, becoming increasingly smaller toward the top. The plant has a nauseating odor when bruised. Woodland groundsel more often is found along roads and in disturbed areas in the forest, while common groundsel is a weed of fields and gardens and the waste areas nearby.

For more information

 

 

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Image of common groundsel seed heads   Up close image of common groundsel seedheads
Common groundsel plants and seedheads.


   Up close image of common groundsel with tufts of white silk-like hairs.

Images courtesy of Ben Legler

 Last updated August 25, 2008