This is a perennial plant about 2-3½' tall that branches
to abundantly. The stems are light green, terete, and hairy; they
appear to be winged in many locations because of the decurrent
extensions of the leaf petioles. The lower leaves are alternate, while
the upper leaves are usually opposite; they are 2-10" long and ¾-4"
across, becoming smaller as they ascend the stems. The leaf blades are
ovate to oblong-lanceolate and smooth along their margins. The upper
blade surfaces are medium to dark green; they are sparsely to
moderately covered with minute stiff hairs. The lower blade surfaces
are light green; they are hairy along major veins. The petioles are as
long as the leaf blades are shorter (usually the latter); some of the
upper leaves are sessile. The petioles are medium to dark above, light
green below, and more or less hairy.
Nodding cymes of flowers about ¾-2" across terminate the upper
primary stems and lateral stems below. The peduncles and
pedicels of these cymes are light green to purplish green and hairy;
individual peduncles are 1-3" long, while individual pedicels are about
¼-½" long. The flowers are about ¼" across and ½" long (or
longer). Each flower has an elongated campanulate corolla (white, pink,
or purple), a hairy green calyx with 5 lanceolate teeth, 5 inserted
stamens, and a pistil with an exerted style. The calyx is about
one-half the length of the corolla. Along the outer rim of the corolla,
there are 5 small lobes that are recurved. The blooming period occurs
from late spring to mid-summer, lasting about 1 month. Afterwards, each
flower is replaced by 4 nutlets. Individual nutlets are about 4-5 mm.
in length, dark brown or black, ovoid in shape, and somewhat
flattened toward one end. The root system consists of a stout taproot
that is dark brown.
The preference is full sun to light shade, moist to mesic
conditions, and fertile soil containing loam. There are few problems
with insect pests and disease organisms.
Range & Habitat:
Common Comfrey has
in NE Illinois and scattered counties elsewhere within the state (see
Such naturalized plants are uncommon. Common Comfrey
was introduced into North America from Eurasia as a medicinal herb. It
is still cultivated in gardens. Habitats include damp grassy
meadows, riverbanks, vacant lots, areas along roadsides and
railroads, ditches, and waste areas. Areas with a history of
disturbance are preferred.
For North America, little is known
floral-faunal relationships for this plant. According to Müller
(1873/1883) in Germany, nectar-seeking long-tongued bees are the
primary pollinators of the flowers, particularly bumblebees and
Anthophorine bees (Anthophora
); sometimes bumblebees steal nectar
by chewing holes near the corolla bases of the flowers. Müller also
reported that honeybees, Halictid bees, and Syrphid flies (Rhingia sp.
would also steal nectar from the corolla holes that were created
by bumblebees. Common Comfrey is somewhat toxic to mammalian
herbivores and humans because it contains pyrrolizidine alkaloids. Over
a period of time, these alkaloids can cause irreversible liver damage
if the foliage and especially the roots are consumed in sufficient
quantity. Horses, cattle, goats, and pigs are susceptible to being
poisoned; apparently sheep are more resistant to adverse reactions.
A garden in Urbana, Illinois.
The foliage of Common Comfrey is somewhat similar to other
species in the Borage family, particularly Lithospermum latifolium
(American Gromwell), Lithospermum
(European Gromwell), and
(Borage). However, the flowers of Common Comfrey have
campanulate (bell-shaped) corollas with open throats, while the flowers
of American Gromwell and European Gromwell have narrow throats. The
flowers of Borage are even more distinct with their widely spreading
petals and sepals; these flowers are also wider, spanning about ¾-1"
across when they are fully open.