Petasites

Petasites is a genus of flowering plant species in the sunflower family Asteraceae that are commonly referred to as butterburs. They are perennial plants with thick, creeping underground rhizomes and large Rhubarb-like leaves during the growing season. Another common name for many species of this genus is Sweet Coltsfoot.

Characteristics

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

Butterbur can be found in parts of Asia such as Korea, China, and Japan, as well as Europe and North America. They prefer moist environments such as riverbanks, marshes and ditches.

Petasites is very closely related to the genus Tussilago (Coltsfoot), and also related to the genus Senecio.

Medicinal uses

Butterbur extracts may contain harmful components called pyrrolizidine alkaloids if the preparations are not carefully and fully purified. 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. These chemicals are toxic to the liver and may cause cancers. Thus, due to the potential for contamination, taking butterbur supplements is not recommended during pregnancy or breastfeeding. It is safe practice to consume butterbur extract that has been prepared by a reputable laboratory.