Aegopodium podagraria L.
(Apiaceae, formerly Umbelliferae)
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Most of Europe and northern Asia, to eastern Siberia
Goutweed, also known as
bishop's-weed and snow-on-the-mountain, is an herbaceous perennial plant.
It is one of several species of Aegopodium, native to Europe and Asia.
Most leaves are basal, with the leafstalk attached to an underground stem,
or rhizome. The leaves are divided into three groups of three leaflets, making
it "triternate." The leaflets are toothed and sometimes irregularly
lobed. Foliage of the "wild" type is medium green in color; a commonly
planted variegated form has bluish-green leaves with creamy white edges.
Sometimes reversion back to solid green or a mixture of solid green and the
lighter variegated pattern occurs within a patch.
Small, white, five-petaled flowers are produced
in mid-summer. Flowers are arranged in flat-topped clusters (called compound
umbels) and are held above the ground on a leafy stem up to about 3 feet
tall. The seeds are small and elongate, similar in size and shape to carrot
seeds, and ripen in late summer. In contrast to the dense foliage cover produced
by goutweed, flowering shoots are uncommon in densely shaded areas.
The rhizomes of goutweed are long,
white, and branching, superficially resembling those of quackgrass (Elytrigia
repens, also known as Agropyron repens). Patches of goutweed typically
form a dense canopy and can exclude most other herbaceous vegetation. Because
of this, it is often used as a low-maintenance ground cover.
Goutweed is an aggressive
invasive plant that forms dense patches, displaces native species, and greatly
reduces species diversity in the ground layer. Goutweed patches inhibit the
establishment of conifers and other native tree species as well.
IN THE UNITED STATES
Goutweed is currently known to occur in twenty-nine
states in the mid-Atlantic, Northeast and Northwest (USDA
PLANTS map) and is reported to be invasive in natural areas in Connecticut,
Michigan, New Jersey, Pennsylvania, Vermont, and Wisconsin (WeedUS Database).
HABITAT IN THE UNITED STATES
is an ecologically versatile species. It is found in old gardens and flowerbeds,
around shrubs and other plantings, and in a variety of other disturbed habitats
such as felled forests, abandoned fields, and pastures. In Eurasia, goutweed
is primarily a species of deciduous and southern boreal forests, and it expands
aggressively in similar habitats in North America. Goutweed appears to do
best on moist soil and in light to moderate shade, but is highly shade-tolerant
and capable of invading closed-canopy forests.
was apparently first brought to North America as an ornamental during the
early stages of European settlement and was well established in the U.S.
by 1863. In parts of Russia, the leaves are sometimes used as a salad ingredient
and potherb in the spring.
BIOLOGY & SPREAD
Goutweed is vigorous,
rhizomatous perennial that spreads mainly by vegetative means. Patches increase
in size through extension of the rhizome system. The flowers are pollinated
by a wide variety of insects, including beetles, bees, and especially small
flies. The seeds have no apparent morphological features that would facilitate
dispersal. Goutweed seeds require cold stratification to germinate. While
established goutweed plants are highly competitive in shaded environments,
seedlings generally need recently disturbed soil and rather bright light
in order to survive. Goutweed apparently does not form a long-lived seed
bank, and the seeds generally germinate the year after ripening. Establishment
of goutweed seedlings in the shade is rare. The primary vector for dispersal
to new areas is humans. Most goutweed colonies spread to neighboring natural
areas from intentional plantings, or by the dumping of yard waste that includes
variety of methods are available for controlling goutweed, depending on the
extent of the infestation and the amount of time and labor available. Regardless
of the control method used, the patch should be carefully monitored periodically
for a few years. New shoots should be dug up and destroyed. Once goutweed
control has been achieved, revegetation with native or non-invasive exotic
plant materials is recommended. This is particularly important on sites where
erosion is a concern or where other invasive species are likely to colonize
the site if left alone.
There are no biological control
organisms currently available for Aegopodium podograria in North America.
Systemic herbicides such as
glyphosate (Roundup®) that are translocated to the roots and kill the entire
plant are most effective for goutweed control. However, glyphosate is non-specific
and can damage or kill desirable native plants that are accidentally sprayed
in the course of treating the goutweed. Contact herbicides are usually ineffective
because goutweed readily leafs out again after defoliation.
Small patches of goutweed can
be eliminated by careful and persistent hand-pulling or digging up of entire
plants along with underground stems (rhizomes). Pulled plants can be piled
up and allowed to dry for a few days before bagging and disposing of them.
Be careful to pick up all rhizomes which, if left behind, can reroot and
sprout new plants. For large patches, a team of volunteers or use of herbicide
Where appropriate, frequent
short mowing may control or slow the spread of goutweed in lawns, along roadsides,
and other areas.
Preventing goutweed from photosynthesizing
in early spring (at the time of leaf-out) can control the plant by depleting
its carbohydrate reserves. This can be accomplished by covering the patch
with black plastic sheeting when the leaves start to emerge from the ground
in the spring, and leaving it in place through the summer. A more effective
option is to cut all plants once they've fully leafed out, using a mower,
scythe, or weed-whacker type machine, and then cover the area with plastic.
Covering the plants in mid- or late summer, after they have regained substantial
starch reserves, is probably much less effective.
USE PESTICIDES WISELY: ALWAYS READ THE ENTIRE PESTICIDE LABEL CAREFULLY, FOLLOW ALL MIXING AND APPLICATION INSTRUCTIONS AND WEAR ALL RECOMMENDED PERSONAL PROTECTIVE GEAR AND CLOTHING. CONTACT YOUR STATE DEPARTMENT OF AGRICULTURE FOR ANY ADDITIONAL PESTICIDE USE REQUIREMENTS, RESTRICTIONS OR RECOMMENDATIONS.
NOTICE: MENTION OF PESTICIDE PRODUCTS ON THIS WEB SITE DOES NOT CONSTITUTE ENDORSEMENT OF ANY MATERIAL.
For more information on
the management of goutweed, please contact:
- Steve Garske, Great Lakes Indian
Fish & Wildlife Commission, Odanah, WI, 715-682-6619; steveg at glifwc.org
- David Schimpf, Department of Biology, University of Minnesota - Duluth, Duluth,
MN, 218-726-7265; dschimpf at d.umn.edu
SUGGESTED ALTERNATIVE PLANTS
your local native plant society for other species suitable for your area
Steve Garske, Great Lakes Indian Fish & Wildlife
Commission, Odanah, WI
David Schimpf, Department of Biology, University of Minnesota - Duluth, Duluth,
Wayne Owen, U.S.D.A. Forest Service, Washington,
Jil M. Swearingen, National Park Service, National
Capital Region, Center for Urban Ecology, Washington, DC
David Schimpf, Department of Biology, University
of Minnesota - Duluth, Duluth, MN
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