Petasites albus aka White Butterbur

Petasites albus is also known as white butterbur. It belongs to the daisy family, Asteraceae. Its native range runs from Europe to the Caucasus. It also includes Algeria, but not Britain or Ireland. This plant lives for more than two years. It grows in temperate regions from rhizomes, or underground stems. It grows in woods, planted woods, roadsides, and waste ground. Many of these sites have damp soil.

Plants grow fast to about 2 feet (0.6 metres) tall. They spread to about 3.3 feet (1 metre) wide. They make useful ground cover where space allows. Their spread makes them hard to fit into small gardens. Flowers bloom from April to May. Seeds ripen in May. Each plant has either male or female flowers. Insects carry pollen between the flowers. Plants need both sexes nearby to set seed.

White butterbur grows in normal garden soil but likes richer ground. Deep soil with plenty of humus suits it best. Keep soil moist, but do not let water stand in it. It grows in sand, loam, and clay, even heavy clay. The soil can be slightly acid, neutral, or slightly alkaline. Part shade suits it best. It also copes with shade and full sun. Plants For A Future lists USDA hardiness zones 4–8.

Its best garden use is ground cover in large, wilder spaces. It suits the edges of woods and sites with patchy shade. It can grow among coarse grass cut each autumn. But its strong spread can take over a small bed. Plants For A Future calls it invasive. This conflicts with the source's weed flag. You can raise more plants with ease by dividing them. Large pieces can go straight into their final growing sites. Small pieces do better in pots first, under light shade.

Plants For A Future lists cooked leaf stalks as edible. It gives the plant a modest rating for food use. It also notes past uses of leaves and roots as medicine. People used these parts to treat coughs, wounds, and ulcers. These past uses do not prove that they help or are safe. The source lists no known hazards. This does not mean the plant is safe. It also notes that people once used leaves to cover their heads. The supplied evidence gives no pest or disease details for this species.