- Name also: Water Horehound, Gypsywort, Gipsy-wort, European Bugleweed, European Water Horehound
- Family: Mint Family – Lamiaceae (Labiatae)
- Growing form: Perennial herb. Rootstock slim, runners delicate and long.
- Height: 20–80 cm (8–32 in.). Stem often unbranched–sparsely branched, 4-edged, hairy, often with reddish base.
- Flower: Corolla almost regular (actinomorphic), with white and red dots, approx. 4 mm (0.16 in.) long, fused, long-tubed, hairy. Upper lip slightly convex, with notched tips, lower lip 3-lobed, central lobe longer than lateral lobes, round-tipped. Calyx virtually regular (actinomorphic), campanulate (bell-shaped), 5-lobed, 13-veined. Stamens 2. Gynoecium composed of 2 fused carpels. Inflorescence terminal, spike-like, comprised of dense, axillary whorls.
- Leaves: Opposite, stalkless–short-stalked. Leaf blade lanceolate–narrowly ovate, hairy, margin large-toothed–pinnately lobed. Inflorescence’s subtending bracts like stem leaves.
- Fruit: 4-parted schizocarp. Mericarps quadrangular, slightly flat, yellowish brown, with oil-secreting glands.
- Habitat: Shores, rich swamps, alder thickets, streams, ditches, sometimes in shallow water.
- Flowering time: July–August.
Gipsywort favours wet habitats. It thrives particularly well on soft-bottomed shores, where rotting plant refuse yields a lot of nutrition. On the other hand, flowing water is a constant source of new food, and on river banks the plant can be found happily growing even on moss-covered rocky outcrops. Wetlands are the life-blood of gipsywort, so their draining and clearing has been detrimental to the species. It is not particularly sensitive to human activity, but it needs wet surfaces. Apart from dampness, it is also limited by temperature. In the warm period that followed the last Ice Age its habitat was much larger and stretched all the way up to the Lapland border. The separate, northernmost stands are probably a legacy of that time. This can be seen in the way that seeds in these stands often fail to ripen in cool summers. Gipsywort is however able to remain in its habitat by spreading vegetatively through its subterraneous runners and waiting for especially favourable conditions.
Like many other Mint family plants, the lower lip on gipsywort’s flowers has a red mark which is a nectar indicator for pollinating insects. Individual flowers are very modest in size, but the dense white whorls they form are certainly eye-catching. The carpels have adapted to float well in their wet environment and can travel far to new habitats. The plant has no fragrance at all, which is quite unusual for the Mint family. It also lacks the four stamens that are also typical, having only two vestigial ones. It is the only representative of its genus in Finland. Gipsywort has been used to dye wool, linen and silk black – and it has even been used in the past as make-up!