Perennial sow thistle (Sonchus arvensis)
Roots: Extensive, may penetrate soil five to ten feet deep, new plants produced by small root pieces.
Stems: Milky sap throughout the plant, erect, 2-5 feet tall,
Leaves: Deeply lobed to nearly entire, clasping base, mildly prickly margins but lack spines on the lower midrib.
Seed: Tufted, spread by wind.
Flowers: Yellow, up to 2 inches wide with flower stalks and flower base (bracts)covered with gland tipped hairs.
Origin: Eurasia or Europe
Poisoning: Unknown