Petasites is a genus of flowering plants in the sunflower family, Asteraceae,[3] that are commonly referred to as butterburs[4][5][6] and coltsfoots.

[7] They are perennial plants with thick, creeping underground rhizomes and large rhubarb-like leaves during the growing season.

The genus name is derived from the Greek word πέτασος petasos, from the plant's broad leaves resembling a wide-brimmed hat.

Toman The short spikes of flowers are produced just before the leaves in late winter (e.g. Petasites fragrans[4]) or spring, emerging with only a few elongated basal bracts and are usually green, flesh coloured or dull white depending on the species.

[11][18] Although mainly well tolerated, the adverse effects of butterbur reported in clinical trials include mainly gastrointestinal problems, such as nausea, flatulence, and belching.

[15] However, the Canadian Headache Society still recommends its use in migraine prevention for a selected number of patients based on their clinical features and co-existing disorders.