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.