Comfreys

Comfreys refers to plants in the genus Symphytum, commonly known as comfrey. They are herbaceous perennials in the family Boraginaceae, native to Europe and Asia and widely cultivated elsewhere. The two best-known cultivated species are Symphytum officinale (common comfrey) and Symphytum x uplandicum (Russian comfrey).

Description and taxonomy: Comfreys grow to about 0.5 to 1.2 meters tall, with large, rough, hairy leaves and clusters of tubular, bell-shaped flowers that are typically purple, pink, or white. They spread by rhizomes and can be difficult to eradicate. The genus comprises several species and hybrids, and common names include common comfrey and knitbone, though precise names vary by region.

Uses and safety: In traditional herbal medicine, comfrey has been used topically for skin healing, bruising, sprains, and inflammatory conditions. Preparations such as poultices and salves are common. Comfrey contains allantoin and other compounds believed to promote cell proliferation, along with rosmarinic acid with anti-inflammatory properties. However pyrrolizidine alkaloids (PAs) present in the plant can cause liver damage if ingested or absorbed, prompting caution. As a result, many health authorities advise against internal use and recommend limiting or avoiding topical use, especially on broken skin. Some PA-free extracts exist for topical use, and regulatory status varies by country.

Cultivation and horticulture: In gardens, comfrey is grown as a medicinal herb and soil improver, valued for high nitrogen content and its use as a green manure or compost activator. It can spread aggressively via rhizomes and may be considered invasive in some settings.