Leaves: blades 1-15(-30) × 1-7(-10) cm. Heads 5-25(-100+). Calyculi: bractlets keeled in fruit, 0.5-1 mm. Involucres 5-10 × 3-4 mm. Phyllaries 3-9 mm. Corollas 7-10 mm. Cypselae 3-5 mm. 2n = 12, 14, 16. Flowering Apr-Sep. Mesic woods, sheltered waste areas, roadsides, stream banks; 50-1900 m; introduced; Greenland, B.C., Ont., Que., Sask.; Alaska, Ariz., Ark., Calif., Colo., Conn., Idaho, Ill., Ind., Ky., Maine, Md., Mass., Mich., Mo., N.J., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis.; Eurasia. Lapsana communis is widely distributed in North America. It is easily recognized by the abruptly constricted lyrate leaves with relatively large terminal lobes, heads of relatively small flowers with yellow corollas, keeled phyllaries, and epappose cypselae. It is aggressively weedy and often found in shady disturbed sites. The milky juice of L. communis is said to be soothing to sensitive skin, particularly on the nipples of nursing mothers.
Hirsute to subglabrous weed 1.5-15 dm; lvs thin, petiolate, with ovate to subrotund, obtuse or rounded, toothed or occasionally basally lyrate blade 2.5-10 נ2-7 cm, progressively less petiolate and eventually narrowed upwards; heads naked-pedunculate, several or many in a corymbiform or paniculiform infl; invol 5-8 mm, with 8 inner bracts; fls 8-15; achenes 3-5 mm, glabrous, curved; 2n=12, 14, 16. Woods, fields, and waste ground; native of Eurasia, now found throughout our range. June-Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.