Swamp Thistle is a native biennial thistle adapted to wet habitats, growing 3–8 feet tall in marshes, fens, and wet meadows across eastern North America. It produces numerous small, rosy-purple flower heads that bloom in late summer. Unlike most thistles, the bracts of Swamp Thistle lack prominent spines — the specific epithet 'muticum' means 'blunt' or 'lacking a point.' It is an important native plant supporting native bees and butterflies.
Best time to see a Swamp Thistle
The best time to see a Swamp Thistle is August–September, when about 67% of U.S. sightings happen, based on 2,918 research-grade iNaturalist observations.
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Recent Swamp Thistle sightings near you
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