Petasites

Petasites is a genus of herbs with leaves in the shape of a heart in the family Asteraceae. The common English name of petasites is "Butterbur". Plants of this genus grow near rivers and other water places in Europe, Asia and North America.
In general, the leaves are very big. His root is very long and grows very quick. Flowers are white, yellow, white-yellow or white-red, they are small and in a great number.
Butterbur is used in medical purposes, but there is a poison in all parts of the plant.
Some species of Butterbur are cultivated as a garden plant.