Colorado
List C
Identification
Growth form: Biennial
forb
Flower: Flowers
are purple and are borne in clusters at the ends of
branches.
Seeds/Fruit: Mature
flower heads form a prickly bur that readily sticks to
clothing or animals.
Leaves: Stem
leaves are alternate, broadest at the leaf base and somewhat
diminished upward. Leaf margins are toothed or wavy, and the
entire leaf is wooly beneath and dark green above. Rosette
leaves are large, hairy, and heart-shaped.
Stems: Mature
plants are 3-7 feet tall. The stem is erect, coarse, and
much branched.
Roots: Large
fleshy taproot
Seedling: Leaves
of the rosette stage are large, simple and usually
heart-shaped (Stubbendieck et al. 1995).
Similar Species
Exotics: Arctium
lappa has larger heads on longer peduncles, and is less
common. Cocklebur (Xanthium strumarium) has smaller,
spiny-margined leaves.
Impacts
Agricultural: Common
burdock is not considered a problem in crops since it is
intolerant to cultivation. Livestock are fond of common
burdock and the foliage imparts a bitter taste to the milk
if it is eaten in large quantities. Common burdock burs can
become entangled in the hair of sheep damaging the quality
and reducing the value.
Ecological: Due
to its biennial nature, common burdock is confined to areas
that are not severely disturbed on an annual basis.
Human: Because
of its diuretic effects, common burdock has been listed as a
poisonous plant (Gross et al. 1980).
Habitat and
Distribution
General
requirements: Common burdock can commonly be found
growing along roadsides, ditchbanks, in pastures and waste
areas. It generally prefers riparian areas that have moist,
fertile soils with high nitrogen contents.
Distribution:
Established throughout much of the United States. Very
common in central and north central Colorado.
Historical: Common
burdock is a native of Eurasia. The hooked spines of the
flower heads gave rise to the idea of Velcro (Whitson et al.
1996).
Biology/Ecology
Life cycle: The
bulk of germination occurs in early spring (Gross et al. 1980).
During the first year the plant forms a rosette. The
following year the plant produces a stout, grooved, rough
stem with numerous branches. Flowering and seed production
occur from July to September. Seeds are mature by September
and are shed continuously throughout the autumn, winter, and
following spring.
Mode of
reproduction: Seed
Seed production:
Common burdock typically produces between 6,000-16,000 seeds
per plant.
Dispersal:
Bur-like seed heads are readily dispersed by sticking to
animal fur or clothing.
Hybridization: Likely
to hybridize with other Arctium species.
Control
Integrated
Management Summary
As with other plants
which reproduce solely by seed, integrated management
efforts must include the elimination of seed production and
the depletion of the seed bank. Combine herbicide or tillage
treatment of rosettes with removal of seed heads from any
plants that have bolted. Preventing dispersal of burs is
particularly important.
References
Gross, R.S.,
P.A. Werner, and W. Hawthorn. 1980. The biology of
Canadian weeds. 38. Arctium minus (Hill) Bernh.
and A. lappa L. Canadian Journal of Plant Science
60:621-634.
Stubbendieck,
J., G.Y. Friisoe and M.R. Bolick. 1995. Common burdock. Weeds
of Nebraska and the Great Plains. Nebraska
Department of Agriculture, Bureau of Plant Industry,
Lincoln, Nebraska. pg. 77.
Whitson, T.D.(ed.),
L.C. Burrill, S.A. Dewey, D.W. Cudney, B.E. Nelson, R.D.
Lee, R. Parker. 1996. Common burdock. Weeds of the
West. Western Society of Weed Science, in
cooperation with the Western United States Land Grant
Universities Cooperative Extension Services, Newark CA.
pg. 56.
