Comfrey, belonging to the genus Symphytum, is a robust, herbaceous perennial plant frequently encountered in gardens and wild areas across temperate regions. Identifying this plant requires close attention to its specific visual characteristics. This guide details the physical traits of comfrey, focusing on the features that allow for accurate visual identification, including its leaves, stem structure, flowers, and growth habits.
The Defining Features: Leaves and Stem
Comfrey plants grow as a stout, erect herb, typically reaching heights between two and four feet, forming dense, bushy clumps. The stems are hollow, often branched, and covered in stiff, bristly hairs. This coarse hairiness gives the entire plant a rough, scratchy texture.
The leaves are large, broadly lance-shaped or ovate-lanceolate, measuring up to ten inches long at the base of the plant. Their texture is rough due to a dense covering of fine, stiff hairs on both the dark green upper surface and the paler underside. The margins of the leaves are smooth and lack teeth.
The most distinct visual trait is the way the leaves attach to the stem, which is described as decurrent. The base of the leaf, particularly the middle and upper leaves, extends downward along the main stem. This extension forms prominent, continuous green flanges or “wings,” making the stem appear distinctly winged.
Flowers and Root Structure
Comfrey flowers are small, tubular, or bell-shaped, and hang downwards in clusters at the tips of the stems. These clusters are coiled before they open, a characteristic inflorescence shape known as a scorpioid cyme, typical of the borage family. The flowers feature five shallowly lobed petals fused into the distinct tube shape.
Flower color varies widely across the species, appearing in shades of cream, white, pink, purple, or blue. The plant blooms from late spring through the summer months, typically between May and August. Beneath the ground, the root structure consists of a large, coarse, spindle-shaped taproot. This deep-penetrating root is thick, tuberous, and has a characteristically black outer coating.
Distinguishing Between Comfrey Varieties
The two varieties most commonly encountered are Common Comfrey (Symphytum officinale) and Russian Comfrey (Symphytum x uplandicum). Differentiating them relies on differences in growth habit and floral color. Common Comfrey is a stout plant with lighter flowers, typically white, cream, or pale pink. Its decurrent leaf wings run fully down the stem to the next leaf node.
Russian Comfrey, a hybrid species, is often more vigorous and taller, reaching up to six feet in height. Its flowers are usually darker, presenting in shades of dark purple, violet, or blue. The distinctive wings created by the leaves on the stem are narrower on Russian Comfrey and may not extend completely between the nodes.
Preferred Habitat and Growth Cycle
Comfrey is a resilient perennial herb that often survives for twenty years or more due to its deep root system. It is a vigorous grower that emerges in mid-spring and flowers throughout the summer. The plant tolerates a wide range of conditions, thriving in full sun to partial shade.
It is frequently found in moist, nitrogen-rich locations, such as along riverbanks, ditches, and in damp meadows. It is also common on roadsides, waste ground, and in disturbed areas, demonstrating its adaptability. Once established, the deep taproot allows the plant to access water and nutrients from below the surface, making it drought-tolerant.