Petasites japonicus subsp. giganteus

Butterburs are tall, dioecious perennials of the subfamily Asteroideae. They have flowering stems that emerge in late spring, and grow taller at the fruition stage. At the final stages of flowering, green rosette leaves emerge from the ground. They grow over the summer to become up to one metre wide. Butterburs spread vegetatively from rhizome fragments.Japanese butterbur has yellowish flowers and only male plants exist in Finland, and throughout the Nordic countries. Common butterbur (Petasites hybridus) usually has deep purple flowers.