Decodon verticillatus aka Swamp Loosestrife

Decodon verticillatus goes by swamp loosestrife and water willow. It belongs to the loosestrife family, Lythraceae. Its native range spans eastern Canada and the central and eastern United States. It grows from Ontario and Maine south to Florida and Louisiana. Its range also reaches southern Illinois along the Mississippi River. This wetland plant grows in marshes, swamps, bogs, and fens. It also grows beside ponds and small lakes.

This perennial has a woody base and many slender stems. Garden plants reach 6–8 feet [1.83–2.44 metres] tall. They can spread to about 8 feet [2.44 metres] wide. The stems grow 3–8 feet [0.91–2.44 metres] long. They bend back or arch, giving the plant a weeping form. Most stems have no branches. Its willow-like leaves hang over the edges of water. The arching growth suits a place beside a large pond.

Pink to rose-purple flowers appear in July and August. These showy blooms add summer colour to wet planting sites. Chicago Botanic Garden lists the plant as attracting birds and butterflies. Both its flowers and its form offer landscape interest. It can serve as a single specimen or a hedge. It also suits planting schemes where it can spread. Large waterside spaces give it room to develop its broad form. Missouri Botanical Garden does not recommend it for small gardens.

Grow swamp loosestrife in full sun or partial shade. It grows well in wet soil and on muddy banks. It also grows in still or slow-moving water. Plants can stand in water to 2 feet [0.61 metres] deep. Their shoots rise above the water surface. Missouri Botanical Garden describes this plant as easy to grow. Both garden sources give USDA hardiness zones 3–9. Moist to wet ground suits its use along water margins.

Allow for spread when choosing a planting site. Stems can form new plants where their tips touch wet ground or water. This clonal growth can help it spread fast along shorelines. Missouri Botanical Garden rates its maintenance needs as medium. It reports no major insect or disease problems. Japanese beetles can still cause trouble in some places. The supplied sources give no information on edible parts or toxicity.