Decodon verticillatus
swamp loosestrife
Overview
Decodon verticillatus is a deciduous wetland subshrub in the loosestrife family (Lythraceae), with long, arching, four- to six-angled stems 3-8 feet (0.9-2.4 m) long that bend back to the water and root where their tips touch wet ground. Submerged stem bases develop thick, spongy, pale aerenchyma tissue that aids flotation and oxygen transport. The lance-shaped leaves, 2-6 inches (5-15 cm) long, are arranged in whorls or pairs along the stems. In mid- to late summer, clusters of bell-shaped magenta to pink-purple flowers, each 0.4-0.6 inch (10-15 mm) wide with crinkled petals, form in the upper leaf axils. The flowers carry stamens of differing lengths, a trait that promotes cross-pollination by bumblebees. Foliage turns red to purple in autumn before dropping. D. verticillatus grows in standing water and saturated soils at the margins of ponds, lakes, swamps, and slow streams across eastern North America. Its tip-rooting stems let it form dense, spreading colonies that can crowd shorelines, and it grows poorly where soil dries out.
Native Range
Native to eastern North America, from Nova Scotia and Ontario south to Florida and Louisiana and west to Minnesota. It grows in shallow standing water and permanently saturated soils along pond and lake edges, in swamps and marshes, and beside slow-moving streams.Suggested Uses
Grown at the margins of ponds, lakes, and constructed wetlands and in rain gardens that stay wet, where its arching stems stabilize banks and shorelines. The summer flowers support bumblebees and other pollinators, and the colonies give cover to waterfowl and aquatic wildlife. Its spreading habit suits large naturalized water features rather than small ponds.How to Identify
Appearance
Size & Dimensions
Height3' - 8'
Width/Spread3' - 6'
Bloom Information
Flowers in mid- to late summer, mainly July through September, with clusters opening along the upper stems over several weeks. Bloom is heaviest on stems in full sun above the water. Flowering ends as the foliage begins its autumn color change.
Detailed Descriptions
Flower Description
magenta to pink-purpleFoliage Description
medium greenGrowing Conditions
Sun Requirements
Requires 4-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight