What Is Ground Ivy?
Ground ivy ($Glechoma hederacea$) is a low-growing, perennial evergreen that is widely considered an invasive lawn weed throughout much of North America, where it is also known as creeping charlie, gill-over-the-ground, and alehoof. Despite its name, it is a member of the mint family, not the true ivy family, which includes English ivy. The plant is identifiable by its scalloped, kidney-shaped leaves and square stems, which produce small purple flowers in the spring. Ground ivy has a strong, minty aroma when crushed, which helps distinguish it from other look-alike plants.
Historically, ground ivy has been used for both culinary and medicinal purposes. European settlers brought it to North America for these uses. It was once used as a flavoring and clarifying agent in brewing beer before hops became popular, leading to the name "alehoof". Medicinally, it was used to treat various ailments, though its efficacy and safety in modern practice are not well-established.
Toxicity to Animals
Horses and Livestock
For large grazing animals like horses, ground ivy can be highly toxic and dangerous, especially when consumed in large quantities. The toxicity is primarily a concern when other forage is scarce, or when ground ivy has been inadvertently mixed into hay supplies.
Symptoms of ground ivy poisoning in horses can include:
- Excessive salivation (slobbering)
- Sweating
- Dilated pupils
- Labored breathing
- Pulmonary edema (fluid in the lungs) in severe cases
While rarely fatal, the effects can be severe. Fortunately, the plant's bitter taste often deters horses and cattle from eating it in large enough amounts to cause serious harm. However, horse owners must be vigilant, especially when feeding hay sourced from areas with heavy ground ivy infestations.
Household Pets: Dogs and Cats
For dogs and cats, ground ivy is considered toxic, but symptoms are typically less severe than in horses. Ingestion can cause gastrointestinal upset, but the animal would need to consume a significant amount to experience severe effects. As with other plants, the severity of symptoms depends on the animal's size, overall health, and the amount consumed.
Common symptoms of ground ivy ingestion in pets include:
- Vomiting
- Diarrhea
- Excessive drooling
- Lethargy
- Abdominal pain
If you suspect your pet has eaten ground ivy, it is best to contact your veterinarian for guidance.
Toxicity to Humans
General Population
Research on ground ivy's toxicity in humans is limited. It is generally considered only mildly toxic when consumed in excessive amounts over a long period. In traditional culinary use, only small quantities were added to food. Compounds like pulegone and other volatile oils are present in the plant, and in high concentrations, they can cause health issues. Some sources report that high doses can irritate the digestive system, kidneys, and liver. For most people, consuming small amounts in a tea or salad is not a major concern, but moderation is key.
Vulnerable Groups
For certain individuals, ground ivy consumption poses a more significant risk:
- Pregnant women: The plant contains pulegone, a compound that can induce miscarriage, making ground ivy potentially unsafe during pregnancy.
- Individuals with kidney or liver disease: The chemical compounds in ground ivy can irritate these organs, potentially exacerbating existing conditions.
- Individuals with seizure disorders: WebMD and other sources advise against using ground ivy if you have epilepsy or a history of seizures.
Comparison of Toxicity: Ground Ivy vs. Other Common Plants
| Feature | Ground Ivy ($Glechoma hederacea$) | Poison Ivy ($Toxicodendron radicans$) | English Ivy ($Hedera helix$) |
|---|---|---|---|
| Family | Mint (Lamiaceae) | Cashew (Anacardiaceae) | Ginseng (Araliaceae) |
| Toxin | Volatile oils (e.g., pulegone) | Urushiol oil | Saponins and polyacetylene compounds |
| Toxicity Type | Ingestion-based for internal organs | Contact dermatitis (skin rash) | Ingestion and contact irritation |
| Risk to Humans | Mildly toxic if large amounts are ingested; serious risks for pregnant women and those with organ issues | Highly allergenic, causing severe, itchy rashes | Mildly toxic if ingested, causing stomach upset; skin contact can cause irritation |
| Risk to Pets | Highly toxic to horses; mildly toxic to dogs and cats | Most dogs are protected by fur, but ingestion can cause upset stomach | Toxic to dogs and cats; causes gastrointestinal and skin irritation |
Safety Precautions for Ground Ivy
1. Proper Identification: Before using ground ivy for any purpose, positively identify the plant. Look for the kidney-shaped leaves with scalloped edges, the square stem, and the minty scent. Other plants, like common mallow or violets, have similar leaves but lack the square stems and mint-like aroma. If in doubt, do not consume it.
2. Moderate Consumption: If using ground ivy for culinary purposes, use it in small quantities as a flavoring rather than a main green. Use younger leaves, which are more tender and less bitter.
3. Avoid High-Risk Groups: Individuals who are pregnant, breastfeeding, or have kidney or liver disease should avoid ground ivy entirely.
4. Keep Out of Reach of Pets: Prevent horses from grazing in areas with heavy ground ivy infestations and ensure pets do not have access to large quantities of the plant. The unpleasant taste of ground ivy usually deters pets, but it is better to be safe.
5. Be Mindful of Pesticides: Since ground ivy is often considered a weed, it may be sprayed with herbicides or pesticides. Foraging from areas where chemical treatments are used is unsafe.
Conclusion
While ground ivy is not considered highly toxic to humans in small, occasional doses, its safety profile is not as benign as many other edible herbs. The most significant health risk is to grazing animals like horses, where large-scale consumption can lead to severe poisoning. For humans, small-scale culinary or medicinal use should be approached with caution and moderated, and it should be completely avoided by pregnant women and those with pre-existing kidney or liver issues. Understanding the specific risks associated with ground ivy helps ensure safety for both you and your animals. You can find more information about poisonous plants and herbs on resources like WebMD, which offers detailed insights into supplements and herbal remedies.
