Menyanthes trifoliata aka Bogbean

Menyanthes trifoliata, or bogbean, is an aquatic herbaceous perennial. It belongs to the Menyanthaceae family. Its native range spans the subarctic and temperate Northern Hemisphere. This includes Britain and Ireland, much of Asia, and North America. It grows beside ponds and in marshy ground. Wild plants often grow in acid soils and shallow water.

Bogbean forms broad mats, with leaves held above the water. Its foliage dies back each year. Garden plants reach about 0.3–1.6 feet (0.1–0.5 metres) tall. Their spread reaches 3.3–4.9 feet (1–1.5 metres). Plants take five to ten years to reach full size. Upright racemes carry white or pale pink flowers. These flower stems reach about 0.8 feet (0.25 metres) high. Each bloom measures about an inch across. Missouri Botanical Garden gives May to June as flowering time. Other sources report flowers through summer, so timing can vary.

Grow bogbean in wet ground or shallow pond water. It suits muddy pond edges, bog gardens, and water gardens. RHS recommends planting baskets for use in large ponds. Water above the planting can reach 0.8 feet (0.25 metres) deep. Clay or loam with acid to neutral pH suits it. It accepts full sun or partial shade. Full sun helps it flower well. RHS rates it H7 for winter hardiness. Missouri Botanical Garden lists USDA zones 3–10.

Bogbean can link open water with planted pond margins. RHS also lists it for wildlife gardens. Care needs are low once the growing conditions suit it. Divide its rhizomes to make more plants. Cut plants back when flowering ends. Containers help limit its spread in small planting areas. Missouri Botanical Garden warns that unconfined plants can spread strongly. Both horticultural sources report few serious pest or disease problems.

Plants For A Future records cooked roots as emergency food. They need treatment to remove their harsh taste before use. That treatment also removes some vitamins and minerals. Bitter leaves have served as a hop substitute in beer. The same source records medicinal use for digestion and inflammation. These uses do not mean the plant is safe to eat freely. Large doses can cause stomach pain, nausea, vomiting, and diarrhoea. Reports also link it with damage to red blood cells. It may worsen existing inflammation or infection in the digestive tract.