Horticulture/Glechoma hederacea

Glechoma hederacea (Ground-ivy) is a an aromatic, perennial, evergreen creeper of the mint family, ../Lamiaceae/, native to Europe and southwestern Asia but introduced to North America and now common in most regions other than the Rocky Mountains. Its common names include Alehoof, Creeping Charlie (or Charley), Catsfoot (from the size and shape of the leaf), Field Balm, Run-away-robin, Ground Ivy, Gill-over-the-ground, and Tunhoof. It is also sometimes known as Creeping Jenny, but that more commonly refers to ../Lysimachia nummularia/.

Description
It can be identified by its round to reniform (kidney or fan shaped), crenate (with round toothed edges) opposed leaves 2–3 cm diameter, on 3–6 cm long petioles attached to square stems which root at the nodes. It is a variable species, its size being influenced by environmental conditions, from 5 cm up to 50 cm tall.

Glechoma is sometimes confused with common mallow (Malva neglecta), which also has round, lobed leaves; but mallow leaves are attached to the stem at the back of a rounded leaf, where ground ivy has square stems and leaves which are attached in the center of the leaf, more prominent rounded lobes on their edges, attach to the stems in an opposite arrangement, and have a hairy upper surface. In addition, mallow and other creeping plants sometimes confused with ground ivy do not spread from nodes on stems. In addition, ground ivy emits a distinctive odor when damaged, being a member of the mint family.

The flowers of Glechoma are bilaterally symmetrical, funnel shaped, blue or bluish-violet to lavender, and grow in opposed clusters of 2 or 3 flowers in the leaf axils on the upper part of the stem or near the tip. It usually flowers in the spring.

Ecology
Glechoma thrives in moist shaded areas, but also tolerates sun very well. It is a common plant in grasslands and wooded areas or wasteland. It also thrives in lawns and around buildings, since it survives mowing. It spreads by stolons or by seed. Part of the reason for its wide spread is this stoloniferous method of reproduction. It will form dense mats which can take over areas of lawn, and thus can be considered an invasive or aggressive weed. It can be a problem in heavy, rich soils with good fertility, high moisture, and low boron content. It thrives particularly well in shady areas where grass does not grow well, although it can also be a problem in full sun.

Uses
Glechoma is sometimes grown as a potted plant, and occasionally as a ground cover. A variegated variety is sometimes commercially available.

While often thought of as a weed because of its propensity for spreading, Glechoma has culinary and medicinal uses which were the cause of its being imported to America by early European settlers. The fresh herb can be rinsed and steeped in hot water to create an herbal tea which is rich in vitamin C. The essential oil of the plant has many potent medicinal properties; the plant has been used for centuries as a general tonic for colds and coughs and to relieve congestion of the mucous membranes. The plant has been demonstrated to have anti-inflammatory properties. It has also been claimed to increase excretion of lead in the urine.

Its medicinal properties have been described for millennia, Galen recommending the plant to treat inflammation of the eyes, for instance. John Gerard, an English herbalist, recommended the plant to treat tinnitus, as well as a "diuretic, astringent, tonic and gently stimulant. Useful in kidney diseases and for indigestion."

Glechoma was also widely used by the Saxons in brewing beer as flavoring, clarification, and preservative, before the introduction of hops for these purposes; thus the brewing-related names, Alehoof, Tunhoof, and Gill-over-the-ground.