Meet the plant
White butterbur (Petasites albus) appears as flowers early in the year (Feb - May) with leaves appearing after flowering. These spiked white flower heads dominate damp riverside areas. The plants leaves are small when the plants are flowering, but later they become much larger, up to 30cm across. They resemble rhubarb leaves, but slightly more heart-shaped and grow low, forming dense carpets completely dominating the ground.
Butterbur has a rhizome root, so spreads readily in damp ground along rivers and road verges. It can regenerate from fragments of rhizome, which can be carried along river corridors by the water. It has invaded many areas of disturbed flood-prone ground.
White butterbur is similar to the native Common butterbur (Petasites hybridus) and the flowers are main distinguishing feature. White butterbur flowers have five narrow white petals, narrower than those of the Common butterbur, with long pale-green sepals, whereas in Common butterbur sepals are shorter. The flowers are all-white, whereas Common butterbur has mauve to purplish flowers. The leaves of White butterbur can be more elongated with a white felt underneath, but are difficult to separate from Common butterbur leaves.
White butterbur's main distribution within GB is concentrated in NE Scotland. It was imported as a garden ornamental from mainland Europe and SW Asia and escaped into the wild.
Read more about White butterbur
White butterbur comes into leaf early in the year and forms a dense overlapping canopy of leaves through which light cannot penetrate. It forms pure patches many metres across and suppresses any native vegetation growth and reduces the variety of native wildlife on the site.
The plant's rhizomes are not as strong and branched as the roots of native plants and so the riverbank is more prone to erosion, which leads to sediment entering the water leading to further problems for aquatic species and risk of flooding downstream.
Management of White butterbur
As White butterbur is not a particularly widespread invasive plant on a GB scale there is little information on its control. However, there is a significant amount of White butterbur within our project area so we are undertaking a trial to establish the most effective removal method for the plant.
We are investigating various methods of removal, including herbicide application at various concentrations, hand digging and strimming. We have also planted native trees and seeded wildflower mixes to see if these plantings help suppress butterbur re-growth. The progress and results of this trial can be read in the case studies.