Glechoma hederacea

The Tale & The Botany: Glechoma hederacea

Glechoma hederacea is a perennial in the Lamiaceae family, closely related to mint and thyme.

Hedera is the genus of the majority of the ivy varieties – referring to the creeping stems that root at the nodes, as an ivy does, forming dense mats of foliage that often carpet shady or moist ground.

The stems are slender and square in cross-section, a typical feature of mint-family plants.

The leaves are opposite, rounded to kidney-shaped, softly hairy, and coarsely scalloped along the edges.

They sit on long petioles and emit a pleasant, mint-like aroma when crushed.

Myths and Legends

Historically, Glechoma hederacea was used in herbal medicine as a cleansing and expectorant herb, and in medieval brewing as a flavoring and clarifying agent before hops became common.

Today, its aromatic leaves and early flowers make it valued by some gardeners as a charming groundcover, especially the variegated form Glechoma hederacea ‘Variegata’.

Extremely hardy and resilient, it remains green through much of the year and spreads wherever it finds a little moisture and shade.

European settlers transported Glechoma hederacae everywhere, as an edible and medicinal plant. It is in fact rich in essential oils, vitamin C, provitamin A, zinc, iron, silicon, molybdenum, and calcium.

However, its rapid growth rate and its rhizomatous root systems meant that it quickly colonized the areas it was was introduced to.

Glechoma hederacea is still considered invasive in several states in the United States.

Floral Morphology

From early spring to early summer, Glechoma hederacea produces small, funnel-shaped flowers of soft violet-blue to mauve, usually arranged in pairs or small clusters in the leaf axils.

Each flower has a two-lipped corolla—the upper lip short and hooded, the lower lip broad and three-lobed, marked with deeper purple veins that guide pollinators.

The flowers are arranged in groups of two to four in the leaf axils and borne on upright stems 5–30 cm tall.

The corolla is bilabiate, 1–2 cm long, with an upper lip divided into two lobes and a broader lower lip with three lobes, marked with purple spots on the upper lip.

These flowers emit a sweet fragrance that attracts pollinating insects.

The blooms are a valuable nectar source for early bees.

After flowering, the plant forms small brown nutlets (achenes) enclosed within the persistent green calyx.

Though modest in size, the plant’s creeping growth habit allows it to spread rapidly, making it both an attractive groundcover and, in lawns, a sometimes persistent weed.

Ecology

In Europe, in the wild, it grows in meadows, along roadsides, in uncultivated lands, and in deciduous woodlands.

Ground ivy thrives in shady or partially shaded places, preferring moist, fertile, well-drained soil, but it can tolerate a wide range of conditions and even survive in sun if the soil remains cool.

It has naturalized widely in North America, where it grows in woodlands, hedgerows, lawns, and along paths > more invasively than not.