Basic Information

Common Name: Symphytum (Genus)

Scientific Name: Symphytum

Native Habitat: Europe and Asia

History / Discovery / Cultivator

The genus Symphytum, commonly known as comfrey, has a rich history intertwined with traditional medicine and agricultural practices. Its very name, derived from the Greek “symphyo” meaning “to unite” or “grow together,” hints at its historical use in healing wounds and broken bones. While pinpointing a single “discoverer” is impossible, the plant’s therapeutic properties were recognized and documented as far back as ancient Greece and Rome.

Dioscorides, a Greek physician and botanist in the 1st century AD, described comfrey’s ability to heal wounds and fractures in his influential materia medica, De Materia Medica. Pliny the Elder, a Roman naturalist, also wrote about its medicinal uses. These early writings established comfrey’s reputation as a healing herb, a reputation that persisted for centuries.

Throughout the Middle Ages, comfrey remained a staple in European herb gardens. Monks cultivated it in monastery gardens for medicinal purposes, and it was widely used in folk medicine to treat a variety of ailments, including ulcers, respiratory problems, and arthritis. The plant’s popularity stemmed from its supposed ability to stimulate cell growth and promote tissue repair.

In more recent centuries, comfrey gained recognition in agricultural circles as a valuable soil amendment and livestock feed. British organic gardening pioneer Lawrence D. Hills played a significant role in popularizing comfrey in the 20th century. He recognized its exceptional ability to accumulate nutrients from the soil, making it an ideal source of compost and liquid fertilizer. Hills established the Henry Doubleday Research Association (now Garden Organic), which conducted extensive research on comfrey’s horticultural uses.

Hills specifically focused on the Russian Comfrey, Symphytum x uplandicum, a hybrid of S. officinale and S. asperum, which proved to be a particularly productive and non-invasive variety. He promoted its use as a “cut-and-come-again” green manure, emphasizing its ability to improve soil fertility and support sustainable gardening practices. The Bocking cultivars, developed through the HDRA, are still widely available and valued for their high yields and low seed production.

Despite its widespread use and historical reputation, concerns about comfrey’s safety arose in the late 20th century. Studies revealed the presence of pyrrolizidine alkaloids (PAs) in comfrey leaves and roots, which can cause liver damage if ingested in large quantities. This led to restrictions on the sale and use of comfrey as a medicinal herb in many countries.

However, comfrey remains a valuable plant in organic gardening and permaculture systems. Its deep roots help to break up compacted soil, and its leaves provide a rich source of nutrients for compost and mulch. While internal use is generally discouraged due to the PA content, external applications for minor injuries are still sometimes practiced, although caution is advised. The legacy of comfrey is therefore complex, a plant with a long history of medicinal use and agricultural value, tempered by modern scientific understanding of its potential risks. Its cultivation continues to be relevant to gardeners and researchers interested in sustainable and regenerative practices.

Plant Care Summary

Botanical Insights

Adaptations

Comfrey exhibits several notable adaptations that contribute to its survival and effectiveness. Its deep taproot allows it to access water and nutrients from deeper soil layers, making it relatively drought-tolerant and a highly efficient nutrient accumulator. This deep root system also helps to break up compacted soils and improve soil structure. Additionally, comfrey’s fast growth rate and prolific leaf production enable it to quickly capture sunlight and convert it into biomass. This rapid growth also makes it an effective competitor against weeds. The plant’s bristly leaves and stems may offer some protection against herbivores, although it is still susceptible to certain pests. The presence of allantoin, a compound known for its wound-healing properties, is another adaptation that has contributed to its historical medicinal use.

Propagation Methods

Comfrey can be propagated through several methods, each with varying degrees of success:

• Root Cuttings: This is the most reliable method. Dig up the plant in late fall or early spring and divide the root system into sections, each about 2-3 inches long. Plant these root cuttings horizontally in well-draining soil.
• Crown Division: Mature comfrey plants can be divided at the crown (the point where the roots meet the stems) in early spring or late fall. Ensure that each division has a portion of the root system and at least one growing point.
• Seed (Less Reliable): While comfrey can be grown from seed, it is less reliable, especially with hybrid varieties like Russian Comfrey. Seeds often require cold stratification (a period of cold, moist storage) to germinate properly. Also, seedling growth can be slow, and hybrid plants may not come true from seed.
• Stem Cuttings: While less common, stem cuttings can sometimes be rooted. Take cuttings from young, actively growing stems and place them in water or a rooting medium until roots develop.

Toxicology

Comfrey contains pyrrolizidine alkaloids (PAs), which are hepatotoxic, meaning they can damage the liver. The highest concentrations of PAs are found in the roots, followed by the leaves. Ingesting comfrey can lead to veno-occlusive disease (VOD), a condition that obstructs blood flow in the liver and can lead to liver failure, especially with prolonged use or high doses. Symptoms of liver damage can include jaundice (yellowing of the skin and eyes), abdominal pain, fatigue, and nausea.

For Humans: Internal use of comfrey is generally discouraged due to the risk of liver damage. While small, infrequent exposure is unlikely to cause significant harm, regular or high-dose consumption should be avoided.

For Pets (Cats & Dogs): Comfrey is also toxic to pets if ingested. The symptoms are similar to those in humans: liver damage, lethargy, loss of appetite, vomiting, and jaundice. The severity of the reaction depends on the amount ingested and the size of the animal. Veterinary attention should be sought if a pet has consumed comfrey. Even external use on pets should be approached cautiously due to the risk of absorption through the skin.

Common Problems

Pests:

• Slugs
• Snails
• Aphids

Diseases:

• Powdery mildew
• Rust

Other:

• Leaf scorch (Cause: Insufficient watering or excessive sun exposure)
• Overgrowth (Cause: Comfrey can spread rapidly through root fragments, requiring careful management)
• Nutrient Imbalance (Cause: Can sometimes experience issues with nutrient deficiencies, particularly if grown in poor soil)

Rarity & Value

Rarity:

Comfrey itself is not a rare plant; it is widely available in nurseries and garden centers. However, certain cultivars, particularly those with unique characteristics like variegated foliage or specific medicinal properties, may be more difficult to find. Wild populations are also common in some regions. Rarity in comfrey usually applies to specific named cultivars and selections rather than the species itself.

Value:

The value of comfrey typically stems from its horticultural applications. It is a valuable plant for organic gardeners due to its ability to improve soil fertility, provide compost material, and attract beneficial insects. Factors that influence the value of a comfrey plant include:

• Cultivar: Certain cultivars, such as the Bocking varieties developed by Lawrence Hills, are highly valued for their high yields and non-invasive growth habits.
• Size: Larger, more established plants may command a higher price.
• Health: Healthy, vigorous plants with no signs of pests or diseases are naturally more valuable.
• Organic Certification: Comfrey plants grown using organic methods may be more appealing to environmentally conscious consumers.
• Propagation Material: Comfrey roots and crowns are sometimes sold for propagation purposes, adding to their overall value.