Spiraea salicifolia aka Bridewort

Spiraea salicifolia is a shrub in the rose family. It sheds its leaves each year. Its names include willowleaf meadowsweet and willow-leaved spirea. It is native to parts of Europe and Asia, including Japan. It grows near streams, in river valleys, and in woods. In Japan, it also grows in wet, boggy mountain ground. It has spread beyond gardens in parts of the United States. It now grows wild in Wales and northern England too.

This shrub grows fast and forms a round mass of woody stems. Shoots called suckers spread out and form thick patches. The stems grow straight and often have few branches. Their smooth skin ranges from yellow-brown to yellow-gray. Each leaf is simple, with one blade rather than separate leaflets. Leaves grow in turn along the stems, not in pairs. They are narrow and pointed, much like a lance. Each leaf has double teeth along its edge and no hairs. The leaves are green or gray-green.

Small flowers grow in dense, branched clusters called panicles. They are pink or white with a pink tinge. Their scent draws bees and other insects that pollinate them. Chicago Botanic Garden records blooms in May and June. NC State reports blooms through the summer. These reports suggest that growing conditions affect bloom time. The dry fruits, called follicles, split along one side. They let out winged seeds when they open.

This shrub grows best in full sun. It also accepts some shade, including light filtered through trees. It grows in clay, loam, or sand. Moist loam suits it best, but it tolerates some dry soil. Acid to neutral soil avoids problems linked to lime. Chalky soil can make leaves lose chlorophyll and turn yellow. Sources place it in USDA zones 4–8. Plants For A Future reports that it withstands cold near −25°C. Dense clumps can grow weak. Splitting and replanting them can help restore their strength.

Use it for hedges, screens, borders, or sites beside ponds. Its spread helps hold soil along rivers and lakes. NC State lists few serious pest or disease problems. Aphids and cicada caterpillars may be present. Fungi can cause trouble where air does not move well. Young leaves are edible when cooked and contain vitamin C. Plants For A Future lists no known hazards. It also notes past uses of roots and unripe seeds. These reports do not prove that medical use is safe. Nor do they prove that such use works.