Terrestrial invasive species

Nature

Most of these invasive plant factsheets are created from the booklet Minnesota invasive non-native terrestrial plants, an identification guide for resource managers.

Check the additional resources and herbicides table for more information.

Perennial sow thistle (Sonchus arvensis)



Description:

Appearance: Perennial herbaceous plant, 2 - 5' tall erect, single stem, branches near the top into several flower stalks. Broken stems emit a sticky milky bitter juice with a sour odor.

Leaves: Alternate, lower leaves are deeply lobed, upper leaves clasp the stem; similar to dandelion leaves except with teeth ending in small weak prickles.

Flowers: Bright yellow up to 2" wide daisies, blooming from June through August.

Seeds: Tufted, dispersed by the wind.

Roots: Widely spreading white brittle roots penetrating five to ten feet, producing new plants from small root pieces.

Ecological Threat:

  • Spreads vegetatively as well as through windborn seeds. Each tiny piece of root can grow another plant.
  • It colonizes in cultivated fields, pastures, woodlands, roadsides and gardens.
  • It is not a serious threat to intact native plant communities.
  • It is common throughout the U.S. and is considered a noxious weed in Minnesota.

Control Methods:

Mechanical

Cutting and pulling

Chemical

Spraying with glyphosate or triclopyr, a selective broadleaf herbicide


Native Substitutes:

Additional Resources