Petasites

The genus name is derived from the Greek word πέτασος petasos, from the plant's broad leaves resembling a wide-brimmed hat.[8]

Accepted species[1][3]

• Petasites albus – white butterbur – Europe, Algeria, Turkey, Caucasus, India
• Petasites fominii – Republic of Georgia
• Petasites formosanus – Taiwan
• Petasites frigidus – Arctic butterbur or Arctic sweet coltsfoot – Scandinavia, Mongolia, Canada, northern USA
• Petasites hybridus – common butterbur – Europe, Mediterranean
• Petasites japonicus – giant butterbur, fuki – China, Japan, Korea
• Petasites kablikianus – southeastern Europe from Poland to Albania
• Petasites kamengicus – Arunachal Pradesh
• Petasites paradoxus – central + southwestern Europe from Spain to Poland
• Petasites pyrenaicus syn. Petasites fragrans - winter heliotrope - from Azores to Ireland + Tunisia
• Petasites radiatus – Mongolia
• Petasites rubellus – Mongolia, Manchuria, Korea
• Petasites sibiricus – Siberia
• Petasites spurius – Europe, Siberia, Caucasus, Central Asia
• Petasites tatewakianus – Siberia, Russian Far East, northeastern China
• Petasites tricholobus – China, Vietnam, Himalayas
• Petasites versipilus – Sichuan, Yunnan

Species of hybrid origin[1]

• Petasites × vitifolius

Species formerly included[1]

Petasites glacialis (Ledeb.) Polunin - Endocellion glaciale (Ledeb.) 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. It is dioecious, with male and female flowers borne on separate plants.[9]

Butterbur can be found in parts of Asia such as Korea, China, and Japan, as well as Europe and North America.[10][11] They prefer moist environments such as riverbanks, marshes and ditches.[7][12][13][14]

Petasites is closely related to the genera Tussilago and Senecio.

Butterbur has been used for over 2000 years to treat a variety of ailments including fever, lung disease, spasms, and pain.[12] Currently, butterbur extract is used for migraine prevention and treatment of allergic rhinitis, which have the most evidence for its effectiveness.[12][15][16]

Butterbur extracts may contain harmful components called pyrrolizidine alkaloids if the preparations are not carefully and fully purified.[11] The concentration of the toxic alkaloids is often highest in the rhizomes and lowest in the leaves, and may vary depending on where the plants are grown.[17] These chemicals are toxic to the liver and may cause cancers.[23][24] Thus, due to the potential for contamination, taking butterbur supplements is not recommended during pregnancy or breastfeeding.[19] Some sources say it is safe practice to consume butterbur extract that has been prepared by a reputable laboratory.[11] Other sources say no butterbur product is safe: "The cases of liver toxicity appear to have occurred with extracts of butterbur where the pyrrolizidine alkaloids had been removed and only small amounts remained. There is some evidence that other constituents found in butterbur such as the sesquiterpene constituents for example petasin may be implicated in the liver toxicity".[25]

Long-term health effects and interaction of butterbur with other drugs have not been well documented. However, it can theoretically interact with certain blood pressure and heart medications, as well as with drugs that can induce a liver enzyme called CYP3A4 (i.e. St. John's wort, carbamazepine, phenytoin, rifampin); this interaction can potentially lead to increased concentration of the toxic alkaloids.[19]

• Flora Europaea: Petasites species list and distributions
• eFloras search results: Petasites
• Edibility of Petasites: Visual identification and edible parts of sweet coltsfoot.