swamp loosestrife

noun

: a woody perennial marsh herb (Decodon verticillatus) of the family Lythraceae of eastern North America having opposite or whorled lanceolate leaves and magenta flowers in axillary clusters

called also swamp willow

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

• More than 250,000 words that aren't in our free dictionary
• Expanded definitions, etymologies, and usage notes
• Advanced search features
• Ad free!