Coltsfoot

Basal leaves: blades palmately 5–12-lobed or -angled, mostly 5–20+ × 5–20+ cm, margins irregularly denticulate. Cauline leaves mostly 5–25 mm. Calyculi: bractlets 5–15 mm. Phyllaries mostly 7–15 mm. Ray corollas: laminae (2–)4–10 mm. Disc corollas 10–12 mm. Cypselae 3–4 mm; pappi 8–12 mm, ± surpassing involucres. 2n = 60.

Flowering spring–summer. Disturbed sites, sandy or rocky soils, calcareous sites; 0–800 m; introduced; Saint-Pierre and Miquelon; B.C., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que.; Conn., Ill., Ind., Maine, Md., Mass., Mich., Minn., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., Tenn., Vt., Va., Wash., W.Va., Wis.; Eurasia.

Flowering heads of Tussilago farfara close at night (laminae of ray corollas arch and roll inward). The species is becoming an invasive weed in some areas.