What is Petasites?

Petasites is the scientific genus name for several species of flowering plants native to Europe and northern Asia. The plants grow as wildflowers in areas with wet soil, and some varieties are domesticated in flower gardens. Some species of Petasites also have medicinal uses.

The commonly cultivated Petasites japonicus is usually called Japanese butterbur or sweet coltsfoot. Other varieties of P. japonicus include giant Japanese butterbur and variegated Japanese butterbur. Common names for other species in the family include sweet butterbur, white butterbur, common butterbur or bog rhubarb, winter heliotrope, arrow-leaved coltsfoot, and western coltsfoot. The genus name derives from a Greek word for felt hats worn by shepherds, and the common name "butterbur" supposedly stems from a former practice of wrapping butter with the plant's leaves.

Petasites hybridus — the common butterbur or bog rhubarb — is sometimes used to treat migraines. Studies have found that extract from the common butterbur plant reduces migraine occurrence by 48 percent. Butterbur extract also did not have severe side effects. The root of common butterbur has been used as a homeopathic heart stimulant and remedy for fevers and colds.

Most species of Petasites can reach between 18 and 36 inches (about 45 and 90 centimeters), depending on the variety, but the giant Japanese butterbur can range from 4 to 6 feet (about 1.2 to 1.8 meters) tall. The plants bloom in late winter or early spring, before leaves appear. Flowers grow in clusters on thick stalks and have colors ranging from white to light pink to magenta, depending on the species. The blooms attract butterflies, birds, and bees. Large, heart-shaped leaves appear when the blooms begin to die off — the leaves can reach up to 3 feet (about 0.91 meters) in diameter.

Members of the Petasites family like to grow in soil that is always moist or even wet; when grown in gardens, they should be watered frequently. The plants can grow in soil that ranges from mildly acidic to alkaline and in partial shade to full sun. Butterbur varieties are hardy down to a temperature of -20°F (-28.8°C).

Butterbur spreads aggressively, and thus should be planted 3 to 4 feet (about 0.91 to 1.2 meters) apart. It is often considered a nuisance weed or invasive plant where it is not wanted because of the spreading. The spreading can be controlled in a garden by planting the plants in a sunken metal or plastic tub.

Petasites is a genus of flowering plants in the sunflower family, known for its large leaves and rhizomatous growth. It's commonly found in the Northern Hemisphere, particularly in moist, shaded areas along streams and rivers. Petasites species, such as the butterbur, are native to Europe, Asia, and North America, thriving in temperate zones.

Historically, Petasites has been used for medicinal purposes, particularly the species Petasites hybridus, also known as butterbur. It has been used to treat migraines, allergies, and asthma. According to research, extracts from the plant can reduce the frequency of migraine attacks and are sometimes used in herbal remedies for seasonal allergies.

While Petasites may offer medicinal benefits, it's important to note that it contains pyrrolizidine alkaloids (PAs), which can be toxic to the liver and carcinogenic if consumed in high quantities. As such, products made from Petasites should be certified PA-free. Always consult a healthcare provider before using it for medicinal purposes.

Petasites spreads aggressively through its rhizomes, making it a robust colonizer of suitable habitats. In gardens, it can become invasive if not managed properly. To control its spread, gardeners should consider planting it in containers or using root barriers. Regular monitoring and removal of unwanted shoots will help keep it in check.

Yes, Petasites can be used in landscaping, especially in areas where other plants struggle. Its large, attractive leaves can provide an interesting texture and its ability to thrive in wet, shady conditions makes it ideal for rain gardens or along water features. However, due to its invasive nature, careful placement and management are crucial.

Petasites flowers are early bloomers and provide an important nectar source for bees and other pollinators emerging in the spring. The large leaves offer shelter for various insects and small animals. Ecologically, Petasites can help stabilize soil in riparian zones, preventing erosion and supporting the health of aquatic ecosystems.