Swamp Loosestrife - Decodon verticillatus

Swamp loosestrife is a shrubby perennial growing in wet swampy and boggy areas that has 1-3ft long, arching, leafy stems, often rooting at the tips. Its lance-shaped leaves are opposite or in whorls of 3-4 from which deep pink flowers grow in tufts. The deep pink/purple colored flowers occur in dense clusters in the upper leaf axils. 
The flowers mature into seedpods which fall off and float through the swamp or bog and are often eaten by mallards, black ducks, blue-winged teal, and wood duck. Muskrats tend to feed on the swollen and spongy underwater stems.