Weed of the Week 

Produced by the USDA Forest Service, Forest Health Staff, Newtown Square, PA. WOW 02-01-06 

Invasive Plants website: http://www.na.fs.fed.us/fhp/invasive_plants 

CROWN VETCH 

Coronilla varia L.

Common Names: crown vetch, purple vetch 

Native Origin: Europe, southwest Asia and 

northern Africa

Description: Crown vetch is a perennial 

legume in the pea/legume family (Fabaceae 

or Leguminosae. It can form large clumps 

from creeping stems. The stems can be up to 

6 feet long. Crown vetch has rhizomes up to 

10 feet long which allow the plant to spread 

rapidly. The vegetative growth habit can 

rapidly cover and shade out native 

vegetation. A single plant may fully cover 70 to 100 square feet within a four year period. Compound leaves 

consist of 15-25 pairs of oblong leaflets. Pinkish flowers are clustered in umbels on long stalks. The flowers 

develop into narrow, flattened pods. The seeds are reported to be poisonous. Crown vetch blooms from May 

through August. It spreads both vegetatively through rhizomes and through the dispersal of seeds. 

Habitat: 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. It occurs along roadsides and other rights-of-way, in open fields and on gravel 

bars along streams. It can survive in a variety of environmental conditions, but has the highest yields in areas 

with 18 inches or more annual precipitation. It can tolerate up to 65 inches of annual precipitation, as well as 

withstand long periods of drought, but cannot tolerate flooded or anaerobic soil conditions. It prefers sunny, 

open areas, as it is intolerant of shade, and mature plants can withstand minimum temperatures of –28° F. 

Distribution: This species is reported from states shaded on Plants Database map. It is reported invasive in 

CT, IN, KY, MD, MI, MO, NC, NJ, OR, TN, VA, and WI. 

Ecological Impacts: Crown vetch is a serious management threat to natural 

areas due to its seeding ability and rapid vegetative spreading by rhizomes. 

This aggressive exotic is now widespread along roadsides and natural areas. It

becomes problematic when it invades into natural areas, such as grassland 

prairies and dunes, where it works to exclude native vegetation by fully 

covering and shading native plants. It can climb over small trees and shrubs, 

and eventually form large single-species stands. 

Control and Management: 

• Manual- pulling out the entire plant; mowing; prescribed burning may be effective against seedlings or in 

slowing the spread of crown vetch, but will not control large populations 

• Chemical- It can be effectively controlled using any of several readily available general use herbicides such 

as glyphosate, triclopyr, or clopyralid at recommended label rates on the cut stems and foliage. Follow-up 

treatment with herbicide is likely required to control any surviving stems or new seedlings. Follow label and 

state requirements. 

References: http://plants.usda.gov, www.conservation.state.mo.us, 

http://tncweeds.ucdavis.edu/esadocs/documnts/corovar.html, www.forestimages.org, www.nps.gov