Sowthistle - Sonchus arvensis
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Field sowthistle is a glabrous perennial arising from an extensive creeping
root system. The .5 to 1.5 m tall plants exude a milky juice when injured.
The leaves are alternately arranged. The lower to middle cauline leaves
have prickly margins and vary in shape from pinnate-lobulate to dentate
to subentire. The upper leaves are less lobed and have auriculate-clasping
bases. The inflorescence is a head, 2-5 cm wide, with few to several heads
arranged in a corymbiform cluster. The yellow flowers are all ligulate.
The involucral bracts and peduncles have distinctive gland tipped hairs.
The fruit is a ridged achene with a few white bristles.
Sowthistle is common in gardens, cultivated crops, ditchbanks, and waste
areas. The plant is adapted to a number of environments but can be problematic
in areas that have sufficient moisture such as irrigated lands.
Links to more information
US Army Corp Noxious Plant
Website, video, and graphics by Rob Nelson
For more information on this plant or management please contact US Army Corp of Engineers