There are three plants known as creeping Charlie in the United States, but only one of them, Glechoma hederacea, is known to cause an allergic or toxic reaction. G hederacea is a common lawn and garden weed that's also known as ground ivy. The other two plants, Lysimachia nummularia, a perennial also called creeping Jenny, and Pilea nummulariifolia, a houseplant, are nontoxic.
Identifying Glechoma
Ground ivy is a broadleaf weed common to both residential and commercial landscapes. It gets a foothold in shaded, damp lawns and then spreads into sunny areas. Creeping Charlie is also commonly found in disturbed soil, such as abandoned fields and roadsides. The plant has round, scalloped leaves about the size of a quarter. A member of the mint family, it has square stems that are aromatic when crushed. In spring, creeping Charlie produces three-flowered clusters of blue, white, pink or lavender flowers. The plant spreads with creeping stolons that root where they touch the ground. Creeping Charlie is found throughout most of the continental United States and Canada.
Allergic Symptoms
Call 911 immediately if you think you or another human has ingested creeping Charlie, and call your veterinarian if you suspect one of your animals has eaten it. Creeping Charlie is a particular threat to grazing animals such as horses and goats, although other vertebrates, including humans, are affected if they eat the plant. The ingredient in creeping Charlie that causes allergic reactions is the toxin glechomin, which is contained in volatile oils in the plant. Ingesting creeping Charlie causes a number of symptoms: swelling of the throat and respiratory problems are common, as is sweating. Other symptoms include excessive salivation, shortness of breath, panting, dilated pupils, the appearance of anxiety, a bluish discoloration that results from insufficient oxygen and accumulation of fluid in the lungs. Animals that have been autopsied after dying from G. hederacea ingestion exhibit pulmonary edema and an increased amount of blood in the brain. The sap in the stems and leaves can also cause a rash in some people.
Controlling Creeping Charlie
Controlling ground ivy is a challenge. Your best defense is to maintain a thick, dense lawn, especially in the moist, shady locations that creeping Charlie prefers. According to the University of Tennessee Institute of Agriculture, no pre-emergent herbicides exist for ground ivy control, so you will need to use contact herbicides on the plants to eradicate them. You will need to reapply the herbicide several times for effective control. Consult with your garden center or extension service for herbicides approved for use against ground ivy in your state. If you prefer to control ground ivy by hand pulling the plants, wear gloves and wash your hands well after handling the plant.
Medicinal Uses of Glechoma
G. hederacea has a number of medicinal uses. Extracts of the plant are used as an anti-inflammatory and to reduce swelling. In addition, tonics are used for intestinal problems, including kidney stones, and the plant has been tested for use as an anti-cancer treatment. However, because of the possibility of serious allergic reactions to the plant, never attempt to treat yourself with homemade tonics or extracts. Always use products made with Glechoma with the full knowledge and supervision of your physician.
References
- University of Tennessee Extension: Ground Ivy
- University of Nebraska Cooperative Extension: Toxicity of Common Houseplants
- University of Idaho: Equines & Toxic Plants
- Cornell University Department of Animal Science: Plants Poisonous to Livestock
- University of Pennsylvania Veterinary Medicine: Glechoma
- McDaniel College: Ground Ivy
- USDA Plants Database: Glechoma Hederacea
