Common tansy is an introduced perennial herb with stout leafy stems 50-150 cm tall. The leaves are alternate, 5-30 cm long, and 2-3 times pinnate. The heads are 8-15 mm wide and button-like, with yellow disk flowers only (or very short-petaled ray flowers on the margin). Each stem bears several heads in a compact, rather flat-topped cluster. Common tansy is found along roadsides, on railroad embankments, and in other disturbed areas at low elevations.