This information courtesy
of the Colorado Natural Areas Program
Family:
Asteraceae (Sunflower)
Other Names: scentless chamomile, chamomile, mayweed
USDA Code: ANAR6
Legal Status: Colorado Noxious Weed List B
IDENTIFICATION
Lifecycle:
Annual
Growth form: forb
Flower: Flowers are 0.75 inches in diameter and are borne
at the ends of branched stems. Flowers resemble daisies with
white ray flowers and yellow disc flowers.
Seeds/Fruit: Seeds (achenes) are dark brown and grooved.
Leaves:
Leaves are alternate and finely dissected.
Stems: Mature plants are 10-30 inches tall. Stems are
erect, smooth, and highly branched above.
Roots:
Dense fibrous root system.
Seedling:
SIMILAR SPECIES
Exotics:
Matricaria perforata (scentless
chamomile) is locally common on the western slope, and is
sometimes confused with Anthemis arvensis (corn
chamomile) or Anthemis cotula (mayweed chamomile).
Corn chamomile (Anthemis arvensis) is almost
identical to mayweed chamomile but can be identified by its
lack of odor.
Natives: The native Hymenopappus newberryi has few
stem leaves, and is perennial.
IMPACTS
Agricultural: Corn chamomile can reduce crop production.
It is considered unpalatable to livestock and its feed value
is poor (Woo et al. 1991).
Ecological:
HABITAT AND DISTRIBUTION
General requirements:
Corn chamomile is commonly
associated with ruderal habitats. It is found along
roadsides, ditches, in urban areas, waste places, cultivated
fields, and pastures. It can grow in a wide range of soils
but seems to prefer moist, poorly drained soils. Corn
chamomile prefers moist areas and increases in abundance
during years of above average precipitation.
Distribution: Not yet widespread in Colorado.
Historical:
Corn chamomile is a native of Europe that
was introduced into North America as an ornamental or seed
contaminant.
BIOLOGY/ECOLOGY
Life cycle: Annual.
Corn chamomile germinates readily in
the spring and fall. It has a dense, fibrous root system,
which spreads rapidly during wet periods. Late summer and
fall-germinated seedlings may overwinter as rosettes. In the
spring, bolting commences with the elongation of the central
stem. Overwintering plants flower in mid-May and spring
germinated seedlings flower in June. Flowering stops after a
killing frost, usually in October.
Mode of reproduction: Reproduces primarily by seeds.
Occasionally, basal shoots that are lying along the ground
surface will develop adventitious roots along the contact
surface (Woo et al. 1991).
Seed production: Corn chamomile is a prolific seed
producer and can produce up to 960,000 seeds per plant.
Seed bank: Seed may remain viable in the soil for 4-6
years.
INTEGRATED MANAGEMENT SUMMARY
This species is not yet established in Colorado, and
should be a priority for immediate eradication if found.
Prevent the establishment of new infestations by minimizing
disturbance and seed dispersal. Eliminate seed production to
decrease the spread of this annual forb, and continue to
deplete the seed bank for four to six years. Reseeding areas
with perennial grasses for several years will reduce an
infestation.
REFERENCES
Colorado Natural Areas Program. 2000. Creating
an Integrated Weed Management Plan: A Handbook for Owners
and Managers of Lands with Natural Values.
Colorado Natural Areas Program, Colorado State
Parks, Colorado Department of Natural Resources; and
Division of Plant Industry, Colorado Department of
Agriculture. Denver, Colorado. 349 pages.
USDA,
NRCS. 2005. The PLANTS Database, Version 3.5
(http://plants.usda.gov). Data compiled from various sources
by Mark W. Skinner. National Plant Data Center, Baton Rouge,
LA 70874-4490 USA
Whitson,
T.D.(ed.), L.C. Burrill, S.A. Dewey, D.W.
Cudney, B.E. Nelson, R.D. Lee, R. Parker. 1996. Mayweed
chamomile. 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. 55.
Woo,
S.L., A.G. Thomas, D.P. Peschken, G.G. Bowes, D.W.
Douglas, V.L. Harms, and A.S. McClay. 1991. The biology of
Canadian weeds. 99. Matricaria perforata Merat
(Asteraceae). Canadian Journal of Plant Science 71:
1101-1119.
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