Illinois Natural History Survey - University of Illinois

Trailing crown vetch (Coronilla varia L.)


Photo by Kenneth R. Robertson, INHS



Trailing crown vetch is an herbaceous legume with creeping stems 2-6 feet (0.6-1.8 meters) long, bearing leaves consisting of 15-25 pairs of oblong leaflets. This species has strong rhizomes, and a reclining growth habit. The pinkish lavender to white clusters of flowers occur in umbels on long, extended stalks. Flowers produce narrow, finger-like pods containing slender seeds that have been reported to be poisonous.

Similar Species
Trailing crown vetch is distinguished from other plants in the legume family by the following characteristics: 1) compound leaves with an odd number of leaflets ranging between 15-25, 2) the presence of leaves and flower stalks arising from the main stem, and 3) the occurrence of flowers in an umbel. Trailing crown vetch should be accurately identified before attempting any control measures. If identification of the species is in doubt, the plant's identity should be confirmed by a knowledgeable individual and/or by consulting appropriate books.

The natural distribution of trailing crown vetch is Europe, southwest Asia and northern Africa. It is introduced or naturalized in the United States from Maine to South Dakota, south to Virginia, West Virginia, Kentucky, Illinois, and Missouri. This species is widely distributed in Illinois, with occurrences recorded from over one-half of the counties.

Trailing crown vetch has been grown extensively in the northern two-thirds of the United States for temporary ground cover, erosion control, and as a green fertilizer crop. It is also used as a bank stabilizer along roads and waterways. This plant prefers open, sunny areas. It occurs along roadsides and other rights-of-way and in open fields.

Life History
Flowers appear from May to August. Trailing crown vetch is a perennial, herbaceous plant that can spread rapidly by seed and its multi-branched creeping root system.

Effects Upon Natural Areas
Trailing crown vetch is a serious management threat to natural areas due to its seeding ability and rapid vegetative spreading by creeping roots. This aggressive exotic is now widespread in Illinois along roadsides and in waste grounds, from where it becomes a serious invader of prairies and dunes.




Initial efforts in areas of heavy infestation
Very little research information is currently available regarding the control of crown vetch. Research has largely been restricted to the establishment and management of the perennial legume for cultural purposes. As a result, a limited number of control measures only recently have been available from unpublished field notes of active natural resource managers. The following controls have met with some success, but field research is needed to adequately address this alien species.
In fire-adapted communities, prescribed burning in late spring can be an effective control.
Prescribed burns may need to be repeated for several years to achieve adequate control.
Where feasible, late-spring mowing for several successive years can control this species.

Initial efforts in areas of light infestation
Same as given above for heavily infested areas.

Maintenance control
A regular fire regime should control this species in fire-adapted communities. In Illinois, trailing crown vetch primarily invades communities that are fire-adapted.

Initial efforts in areas of heavy infestation<br> Same as given above for heavily infested areas. In addition, the following chemical control methods are effective and could be used where prescribed burning or mowing are not feasible.
The herbicide 2,4-D amine (dimethylamine salt of 2,4-D) is a low volatility formulation that can be foliar applied in early spring when crown vetch is growing actively. 2,4-D amine should be applied by hand sprayer at the recommended application rate on the label for spot application. Phenoxy herbicides are broadleaf selective plant growth regulators that will not harm grasses but precautions must be taken in the vicinity of sensitive nontarget plants. To reduce vapor drift, use an amine rather than an ester formulation of 2,4-D. The control area should be spring-or fall-burned to remove accumulated plant litter to insure complete foliar coverage. A follow-up treatment using recommended label rates is necessary to obtain complete results.
The herbicide mecamine (2,4-D plus Dicamba) is effective when foliar applied as a 1% solution to crown vetch plants in a state of rapid growth (spring or early summer before flowering).
In addition, Roundup (a formulation of glyphosate) is a broad spectrum, translocated herbicide that can be foliar applied as a 1 or 2% solution during early spring when the plant is actively growing. Avoid direct application to any body of water, sensitive species, or areas that need to be protected from drift and direct application. Roundup is nonselective and care should be taken to avoid nontarget plants. To insure good foliar coverage, the previous year's growth should be prescribed-burned to eliminate duff accumulation. A follow-up application of Roundup may be necessary the following fall or early spring to combat regeneration from underground parts or seeds.
When applying any herbicide described above, spot application should be done with a hand sprayer and should be uniform such that the entire leaf is wetted. Do not spray so heavily that herbicide drips off the target species. Care should be taken to avoid contacting non-target species. Native plants, left unharmed, will be important in recolonizing the site after crown vetch is controlled. The herbicide should be applied while backing away from treated areas so as not to walk through the wet herbicide. By law, herbicides only may be applied according to label instructions and by licensed herbicide applicators or operators when working on public properties.

Initial efforts in areas of light infestation
Same as given above for heavily infested areas.

Maintenance control
A periodic prescribed fire regime should control this species in fire-adapted communities. Late-spring mowing can be used when fire is not feasible.




No effective biological controls that are feasible in natural areas are known.




Gleason, H. A. 1952. The new Britton and Brown illustrated flora of the northeastern United States and adjacent Canada. Vol 2. The New York Botanical Garden, New York. 655 pp.

Fernald, M. L. 1950. Gray's manual of botany, eighth edition. American Book Co., New York. 1632 pp.

Mohlenbrock R. H. 1986. Guide to the vascular flora of Illinois. Southern Illinois University Press, Carbondale. 507 pp.




Glass, William. 1989. Division of Natural Heritage, Illinois Department of Conservation, Springfield, Illinois.

Nyboer, Randy. 1989. Division of Natural Heritage, Illinois Department of Conservation, Springfield, Illinois.

Packard, Steve. 1989. The Nature Conservancy, Chicago, Illinois.

Schwegman, John. 1989. Division of Natural Heritage, Illinois Department of Conservation, Springfield, Illinois.

West, Andy. 1989. Division of Natural Heritage, Illinois Department of Conservation, Springfield, Illinois.



Written for the Illinois Nature Preserves Commission by:
Jim Heim
Illinois Department of Conservation
Castle Rock State Park
R.R. 2
Oregon, Illinois 61061

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