Perennial sowthistle (Sonchus arvensis)

Description: Introduced to the United States as a seed contaminant. This species is listed under Regulation No. 715 - Seed Law Implementation as a prohibited noxious weed by the Michigan Department of Agriculture.

Habit: Perennial herb with roots that can grow to depths of 5-10 feet deep and creeping rhizomes that can reach 6 feet in length in a single growing season. Entire plant is filled with milky latex.

Leaves: Crowded on lower stems and sparse on upper stems. Can reach up to 6 inches long.

Stems: Erect, hollow, branched (varying from 2 to many per plant), 0.1-0.4 inches (3-10mm) in diameter, and 24-59 inches tall.

Fruit and seeds: Achenes with pappus. Can produces 30 achenes per flowerhead.

Habitat: Native to Europe and western Asia. Can be found in waste grounds, meadows, woods, lawns, and along roadsides, beaches, ditches and river and lake shores.

Reproduction: By seeds that are dispersed by wind, by vertical, thickened roots, and by cylindrical, horizontal, spreading roots.

Credits: The information provided in this factsheet was gathered from the U.S. Department of Agriculture, Forest Service FEIS SONARV.

Individual species images that appear with a number in a black box are courtesy of the Bugwood.org network (http://www.invasive.org). Individual photo author credits may not be included due to the small display size of the images and subsequent difficulty of reading the provided text. All other images appear courtesy of Google (http://images.google.com).

---