Ground ivy, known scientifically as Glechoma hederacea, is a common perennial plant native to Europe that has become a widespread and aggressive weed in North America. Its ability to spread rapidly and form dense, low-growing mats makes it a persistent nuisance. While modern gardeners often view it as a persistent nuisance, this creeping herb holds a long and fascinating history of traditional use.
Identification and Key Characteristics
Ground ivy is easily recognized as a member of the mint family, Lamiaceae, characterized by its distinctive square-shaped stems. The common names of this plant, which include Creeping Charlie and Gill-over-the-ground, are often used interchangeably with the scientific name. Its leaves are a vibrant green, arranged oppositely on the stem, and feature a rounded or kidney-like shape with scalloped edges. A simple test for identification involves crushing a leaf, which releases a strong, pungent, minty, or musky aroma. In the spring and early summer, small, trumpet-shaped flowers emerge on short, erect stems. These flowers are typically a bluish-violet or lavender color and grow in clusters where the leaves meet the main stem.
Growth Habit and Ecological Behavior
Ground ivy is a creeping perennial that primarily spreads horizontally across the soil surface using above-ground runners called stolons. These stolons are capable of rooting at every node they encounter, quickly establishing new, independent plants and forming a dense mat.
The plant’s success is largely due to its high tolerance for conditions where turfgrass struggles, such as shade and moist, poorly drained soil. Its dense, low-growing habit effectively smothers and shades out less vigorous plants, allowing it to dominate lawn areas under trees and shrubs. While it prefers these shaded environments, ground ivy is highly adaptable and can also tolerate full sun, making it a formidable competitor in diverse landscape settings.
Traditional Uses and Safety Concerns
Ground ivy was intentionally introduced to North America by early settlers for its practical applications. One of its most well-known traditional uses was in brewing, earning it the common name “Alehoof.” Before hops became the standard, the plant was used to flavor, clarify, and preserve ale.
In traditional folk medicine, the herb was valued for its purported expectorant and diuretic properties. It was used to treat a variety of ailments, including respiratory issues like coughs and colds, as well as kidney and bladder disorders. The leaves were also consumed in small quantities, added to salads, soups, and vegetable dishes.
Despite its history of human consumption, there are significant safety concerns regarding its use, particularly for animals. Ground ivy is known to be toxic to livestock, especially horses, if consumed in large amounts. The toxicity is often attributed to volatile oils, such as pulegone, which can cause symptoms like excessive salivation, labored breathing, and pupil dilation in grazing animals. Caution is advised for human consumption beyond small, traditional culinary amounts, and self-medication should be avoided.
Strategies for Management and Removal
Non-chemical control, such as manual removal, is difficult because any small segment of the stolon left in the soil can root and regenerate. For small patches, persistent hand-pulling is necessary, ensuring all runners and root fragments are meticulously removed.
Cultural practices focus on improving the health of the surrounding turfgrass, which is the most effective long-term defense. This includes improving soil drainage, aerating compacted soil, and increasing light penetration by pruning overhanging tree branches. Maintaining a dense, healthy lawn through proper fertilization and mowing at a higher height encourages the grass to outcompete the low-growing ivy.
For widespread or severe infestations, chemical control is often the most practical solution, targeting the plant as a broadleaf weed. Herbicides containing active ingredients such as triclopyr or dicamba are generally the most effective. Applications are most successful when the plant is actively transporting nutrients to its roots, typically in the early fall, which helps ensure the systemic herbicide is fully translocated throughout the stolons and root system.