Petasites japonicus subsp. giganteus

Japanese butterbur is native to eastern Asia. In its native range, it is among the first plants to settle on riversides and, for instance, volcanic ash fields. The plant was introduced to Finland as an ornamental. It grows as an escapee or relict in nutrient-rich shore forests, and on shores and field and road banks. It migrates to new habitats as rhizome fragments in transported soil, for example.