Russian, Common and Prickly Comfrey, learning how to know them when you see them.
Common comfrey (Symphytum officinale) is an erect, stout, often branched perennial, 20 – 42 inches tall. The large leaves are broadly lance-shaped. The middle and upper leaves are without stems, but the point at which they attach to the stems extends downward to the stalk. The stalk itself is distinctly winged. The flower color ranges from white or creamy yellow to rose, pin, or light to dark purple, and the corolla lobes are curved backward.
The stamens provide diagnostic characteristics. In S. officinale, the anther (the yellow, pollen-bearing part of the stamen) is about as wide as the filament (stalk) on which it sits. The calyx segments are distinctly lance-shaped (long and narrow). Unlike other comfrey species, S. officinale has smooth, shining nutlets (seeds), but these are rarely seen. In the wild, comfrey occurs in moist grasslands and riverbanks throughout most of Europe, though it is rare in the extreme south; it is a naturalized alien in much of northern Europe and the eastern United States.
Russian comfrey (S. x uplandicum) is a hybrid between common comfrey (S. officinale) and prickly comfrey (S. asperum), and grows four to six feet tall. It has only narrow wings on the main stalk, and they end between the internodes.
The leaves narrowly hug the main stalk. The flowers are dark purple changing to blue or pinkish changing to pink-blue. The short calyx lobes have pointed tips. Though it grows naturally in northern Europe, most populations are patches that have persisted after being introduced into cultivation.
Prickly comfrey (S. asperum) does not have winged stems, and the upper leaves are on very short stalks. The leaf blades do not hug the stem. The stems and leaves are covered with stout, flattened, recurved prickles. The ½-inch-long rose to bluish flowers are usually larger than those of common comfrey, and their lobes are erect.
The anthers are significantly shorter than the filaments. Originating in Southwest Asia, it is naturalized in Europe as well as in parts of the eastern United States.
Steven Fosterlives in Eureka Springs, Arkansas and been an herbalist for over 40 years. He started with the Sabbathday Lake Shaker Community Herb Department in Maine, America’s oldest herb business, dating back to 1799. He started there in the mid-1970s, when comfrey leaf was a major part of their harvest. “I love plants and sharing information and imagery about the human experience with medicinal and aromatic plants.” You can follow Steven through his website.