- Name also: Ground-ivy. Creeping Charlie, Field Balm, Gill Over The Ground, Runaway Robin
- Family: Mint Family – Lamiaceae (Labiatae)
- Growing form: Perennial herb.
- Height: 5–30 cm (2–12 in.), surface runners can be over a metre long. Stem limp, rooting, often reddish, branched inflorescence ascending–erect, 4-edged, short-haired.
- Flower: Corolla irregular (zygomorphic), purple–blue, 10–23 mm (0.4–0.92 in.) long, fused, bilabiate, long-tubed. Upper lip short and flat; lower lip 3-lobed, with dark markings, central lobe with notched tips. Calyx slightly bilabiate, 5-lobed, 15-veined. Stamens 4, of which 2 short, 2 long. Gynoecium composed of 2 fused carpels. Flowers axillary whorls, often one-sided. Sometimes flowers small, unisexual pistillate flowers.
- Leaves: Opposite, stalked, overwintering. Leaf blade almost round–kidney-shaped–broadly cordate, with rounded teeth (crenate), often slightly purplish especially underneath, surface sparsely short-haired, underside with oil-secreting glands. Inflorescence’s subtending bracts like stem leaves.
- Fruit: 4-sectioned schizocarp. Mericarps round, yellowish brown, covered in sticky hairs.
- Habitat: Grove-like forests and hedgerows. Also an ornamental, left-over from old gardens and escape in yards, gardens, banks, waste ground.
- Flowering time: May–June.
Ground ivy is a persistent plant whose leaves and stems stay green under the snow, allowing it to flower early in the spring. Ground ivy’s flowers are usually violet-blue, becoming slightly paler as they age. The colour of the corolla however varies noticeably: in some stands they are a purer blue from the beginning, but sometimes pink or even white. Some plants only have small, unisexual pistillate flowers. Bumblebees are attracted to the flowers, but even so seeds rarely form. It spreads efficiently however through its surface runners – the whole stand in a yard might actually be clones of a single vegetatively-spreading plant. This is probably also another reason for the poor seed production: the seed subject must be fertilized by pollen from another plant, but there might not be any in the area.
Ground ivy’s Finnish name means ground hops, a reference to its use in making beer and wine, as well as its limp growing form. Real hops (Humulus lupulus) gradually replaced ground ivy in this respect already centuries ago. Ground ivy has been cultivated for its medicinal properties in treating both physical and mental problems. It is strong enough that it should be used sparingly as a tea or salad flavouring. The species’ main economic significance nowadays is as a garden ornamental.