Meet the plant
White butterbur (Petasites albus) has large, rounded leaves, up to 30cm, which grow low, forming dense carpets of leaves. They resemble rhubarb leaves, but slightly more heart-shaped. Spiked white flower heads appear early in the year (Feb - May) with leaves appearing after flowering. Although leaves are small when the plants are flowering they later become much larger.
It 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 buttebur has mauve to purplish flowers. The leaves of White butterbur can be more elongated with a white felt underneath, but are difficult to seperate 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, 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 bank 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
The rhizomes of the plant are tough and difficult to eradicate once established. Due to the risk of fragments of rhizome regenerating mechanical control is not recommended, and chemical control is the preferred method.
As there is a significant amount of White butterbur within our project area we are going to be undertaking some trials to establish the most effective removal method for the plant, as in this case, chemical spraying of significant sized patches may not be the most ideal method. We are also going to be looking at site regeneration, as the impact of removing this plant will leave large bare areas of ground, prone to erosion and possible re-establishment of the plant.
The progress and results of these trials will be reported in our case studies.
There will be opportunities for volunteers to assist with White butterbur removal by a variety of methods, and to help undertake habitat restoration works after butterbur has been cleared, such as tree planting and wildflower seeding. Volunteers can also help with monitoring our trial site in terms of evaluating the most successful removal methods and site regeneration.
Where is it?
White butterburr is not widespread within the project area. It is mostly confined to problem areas in the River Spey, River Deveron and River Ness catchments.