coltsfoot, Eurasian perennial herb (Tussilago farfara) of the family Asteraceae (aster family), now a widespread weed in most northern lands. The scaly flower stalk bears a yellow flower head and downy, somewhat dandelionlike fruits. The leaves—appearing after the flowers—are large and vaguely heart shaped. Coltsfoot was long a popular cough remedy. Other plants are sometimes called coltsfoot, e.g., the related winter heliotrope, or sweet coltsfoot (Petastites fragrans), an ornamental. Coltsfoot is classified in the division Magnoliophyta, class Magnoliopsida, order Asterales, family Asteraceae.