Motherwort

Motherwort is an herbaceous perennial of the mint family, probably native to south-eastern Europe and central Asia and now found worldwide, where it is considered invasive in North America. Wikipedia says it has a squarish, often purplish stem, palmately lobed leaves, and pink to lilac flowers that bloom in mid to late summer. Kynes records that from ancient times through the Middle Ages in Europe it was associated with the heart, used for heartburn and heartache, and that the ancient Greeks used it as a sedative, especially for childbirth. It was worn as a charm and sewn into baby clothes to ward off evils, and in the Hebrides garlands of it were worn on Midsummer's Eve while dancing round the bonfire. Wikipedia adds that in fifteenth-century Europe some herbalists held it to protect against evil spirits. Kynes grows it, or keeps a small sachet of its seeds near the front door, to attract peace and happiness, and uses the dried leaves in spells against negative magic.