Lycopus europaeus aka Gypsywort

Lycopus europaeus is also known as gypsywort. It belongs to Lamiaceae, the mint family. This perennial lives for more than two years. It is native to Europe and nearby regions. Its range takes in the Azores and northwestern Africa. It reaches east through Siberia to the western Himalaya. Britain and Ireland also fall within its native range. It grows in temperate zones, often near fresh water. Wild sites include riverbanks, streams and ditches, plus marshes and fens.

The plant forms clumps and spreads through thin rhizomes, or underground stems. RHS size tables give a garden height of 0.3–1.6 feet [0.1–0.5 metres]. They give the same range for its spread. The RHS text also notes growth to 2.6 feet [0.8 metres]. Hair coats the stems, which bear mid-green, oval leaves. The leaves have pinnate lobes, set along each side. They fall in winter. Small white flowers form whorls, or rings, at the upper leaf bases. Each flower spans about 0.013 feet [0.004 metres]. Bloom lasts from midsummer into early autumn.

Grow gypsywort in full sun or part shade. Choose an open site with rich soil that holds moisture. It accepts chalk, clay, loam and sand. Soil may be acid, neutral or alkaline. RHS lists damp soil that drains well, plus poorly drained sites. Its wetland home suits it to bog gardens and pond edges. RHS gives it a hardiness rating of H7. This covers harsh winters in continental Europe. Plants For A Future lists USDA zones 4–8.

Gypsywort suits wildflower beds and wildlife gardens with damp soil. Allow space for its rhizomes when you choose a spot. RHS states that it matures in two to five years. Grow new plants from seed, or split rhizomes in spring. It needs no routine pruning. RHS reports few usual pest or disease problems. Plants For A Future does not flag it as a weed. The plant also yields a black dye.

Plants For A Future lists the root as edible raw or cooked. It calls this food for scarce times, not a usual crop. The same source notes use of the flowering herb as medicine. Uses include astringent remedies, which tighten tissue, and sedatives, which calm. They also include treatments for an overactive thyroid. These records do not show that home use is safe. The plant can make the thyroid grow larger. It can also disrupt thyroid treatment. People with thyroid disease should avoid it. Pregnant people should avoid it too.