- Name also: Common Selfheal, Heal-all, Heart-of-the-earth, Woundwort
- Family: Mint Family – Lamiaceae (Labiatae)
- Growing form: Usually perennial herb.
- Height: 5–30 cm (2–12 in.). Stem base many-branched, ascending–erect, rooting, 4-edged, sparsely short-haired along edged, usually partly purplish.
- Flower: Corolla irregular (zygomorphic), bluish violet, occasionally reddish or white, 8–15 mm (0.32–0.6 in.) long, fused, bilabiate, long-tubed. Upper lip convex, lower lip with toothed margin. Calyx narrowly campanulate (bell-shaped), bilabiate, 5-lobed. Stamens 4, of which 2 short, 2 long. Gynoecium composed of 2 fused carpels. Inflorescence comprised of dense, spike-like, axillary whorls terminating stem.
- Leaves: Opposite, stalked. Blade ovate, blunt-tipped, hairy, with entire margins–sparsely and shallowly blunt-toothed. Inflorescence subtending bracts small.
- Fruit: 4-sectioned schizocarp. Mericarps slightly flattened, yellowish brown, dark-striped, base with soft tissue.
- Habitat: Meadows, dry meadows, pastures, waste ground, banks, lawns, yards, shores, broad-leaved forests.
- Flowering time: July–August.
Self-heal is easy to recognise by its cylindrical inflorescence. It has purple calyxes, and the subtending bracts under every flower give it a cone-like appearance, especially when it is a withering, brown, fruiting inflorescence. Its colloquial Finnish names probably refer to the way it looks similar to the cone-like pistillate inflorescence with hops (Humulus lupulus) – otherwise low-growing self-heal bears no relationship to its climbing namesake. The inflorescence has also brought pine cones, clovers and different kinds of objects to mind. The inflorescence also catches pollinators’ eyes and attracts mainly bees.
Self-heal’s original habitats in Finland were probably shore meadows and river banks, and perhaps also forest clearings and springs. Originally there were not many places that suited self-heal, but the plant has greatly exploited human activity. Initially it received more light from woods and grazing land, and nowadays it can be found quite often growing on park lawns and road banks everywhere except the most northern parts of the country. In habitats that are kept open herbs and grasses are not able to choke self-heal, and by growing low it avoids both being eaten and being chopped by the lawn-mower. Many small meadow plants have become regrettably rare, but self-heal is a particularly adaptable and flexible species. It easily forms ecological races according to its climate and soil, and its appearance tells a lot about the dampness of the soil and how nutritious it is.
NOT TRANSLATED YET. Pihojen ja puistojen maanpeittokasvina suositun, niittyhumalaa kovasti muistuttavan isoniittyhumalan erottaa helpoimmin siitä, että sen kukinto on selvästi ylimmän lehtiparin yläpuolella (niittyhumalalla ylin lehtipari on heti kukinnon alapuolella). Isoniittyhumala on kalkinsuosija ja aidosti luonnonvaraisena sitä tapaa varmimmin Ruotsin puolelta Gotlannista ja Öölannista.