Perennials, mostly 40-150 cm. Stems 1-2+ (ridged), erect, branched distally (glabrous or sparsely hairy). Leaves basal (soon withering) and cauline; petiolate or sessile; blades broadly oblong or oval to elliptic, 4-20 × 2-10 cm, pinnately lobed (rachises ± winged, primary lobes 4-10 pairs, lance-linear to lanceolate or narrowly elliptic, often pinnately lobed or toothed), ultimate margins dentate, faces glabrous or sparsely hairy, gland-dotted. Heads 20-200 in compact, corymbiform arrays. Involucres 5-10 mm diam. Receptacles convex to conic, epaleate. Ray florets 0 (heads disciform, peripheral pistillate florets ca. 20; corollas yellow, lobes 3-4). Disc corollas 2-3 mm. Cypselae 1-2 mm, 4-5-angled or -ribbed, gland-dotted; pappi coroniform, 0.2-0.4 mm. 2n = 18. Flowering Jul-Sep. Disturbed sites (often moist), abandoned plantings; 10-1600 m; introduced; Alta., B.C., Man., N.B., Nfld. and Labr (Nfld.), N.S., Ont., N.W.T., P.E.I., Que., Sask.; Alaska, Ariz., Ark., Calif., Colo., Conn., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.Dak., Tenn., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; Eurasia; widely introduced in New World and Old World. Tanacetum vulgare escapes from and/or persists after cultivation. In the flora area, it is naturalized mostly in the northeastern and Pacific Coast states and provinces and sporadically elsewhere.
From Flora of Indiana (1940) by Charles C. Deam
This is a medicinal plant which has been cultivated in gardens since pioneer times. It has escaped in all parts of the state. Apparently it propagates entirely by underground stems since it is found so sparingly and about the site of a former habitation.
Indiana Coefficient of Conservatism: C = null, non-native
Coarse, aromatic perennial 4-15 dm from a stout rhizome, glabrous or nearly so; lvs numerous, 1-2 dm, nearly half as wide, sessile or short-petiolate, punctate, pinnatifid with evidently winged rachis, the pinnae again pinnatifid or deeply lobed, with broadly winged rachis, the pinnules often again toothed; heads disciform, numerous, commonly 20-200, the disk 5-10 mm wide; 2n=18. Roadsides, fields, and waste places; native of the Old World, established throughout most of the U.S. and adj. Can. Aug.-Oct.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.