Learn which plants thrive in your Hardiness Zone with our new interactive map!

Crown Vetch Poisoning

By Ma Wen Jie ; Updated September 21, 2017

Crown vetch is an invasive perennial plant of the bean family. It grows 2 to 3 feet tall on hairless stems and sometimes relies on nearby plants for growth support. Crown vetch has been declared a noxious weed by the United States Department of Agriculture (USDA) and, as such, should be eradicated whenever possible.


Crown vetch is a ground cover that originated in the Mediterranean region. Crown vetch was introduced to the United States as a form of erosion control in the 1950s, according to Invasive.org. Although the plant has been declared a noxious weed, some people continue to cultivate the plant as an ornamental flower.


Crown vetch grows quickly and is very hardy, thus it seems an ideal plant for erosion control. However, those traits also allow it to grow at the expense of native wildflower and ground cover species. Because it reproduces from both seeds and rhizomes, getting rid of crown vetch can be difficult. Invasive.org offers several suggestions for native alternatives to crown vetch: Spreading dogbane, kinnikinnick, whorled milkweed, Virginia creeper, western brackenfern and American vetch.

Geographical Distribution

Crown vetch is found in all U.S. states except North Dakota and Alaska. It is in all Canadian provinces that border the United States. It is typically found in fields or beside roads. It has been declared invasive and a noxious weed in states such as Oregon, Wisconsin, Missouri, Michigan, Indiana, Kentucky, Tennessee, North Carolina, Virginia, New Jersey and Connecticut, according to Invasive.org.


Crown vetch is a low-growing vine with pink and white flowers that grow in clusters up to 1 inch wide. The compound leaves are 2 to 4 inches long and are made up of 1/2- to 3/4-inch leaflets. Crown vetch pea pods are 1 to 2 inches long.


Removing crown vetch can be difficult once it has become established. The Pennsylvania Department of Conservation and Natural Resources recommends a combined approach to crown vetch mitigation. The plant should be physically removed to try to get as much of the root structures as possible. Once removed, an herbicide should be applied to control regrowth. This process should be repeated for several years. A strong, aggressive native plant should be planted at the site to prevent regrowth of the crown vetch.

Effects of Ingestion

Crown vetch is toxic to birds, plants, animals and people. Eating crown vetch can cause stomach cramps and diarrhea. Crown vetch poisoning often results from children eating the plant, or from people mistaking it for mugwort, an herb commonly consumed in Japan, Germany and Korea that looks similar to crown vetch. Crown vetch poisoning has no treatment. If animals ingest the plant in large amounts, it can cause paralysis or death. If ingested by humans, contact a doctor.


About the Author


Although he grew up in Latin America, Mr. Ma is a writer based in Denver. He has been writing since 1987 and has written for NPR, AP, Boeing, Ford New Holland, Microsoft, RAHCO International, Umax Data Systems and other manufacturers in Taiwan. He studied creative writing at Mankato State University in Minnesota. He speaks fluent Mandarin Chinese, English and reads Spanish.