European marsh thistle, a terrestrial and wetland herbaceous biennial in the Asteraceae family, is an invasive plant that prefers fens, wetlands, and disturbed sites such as roadside ditches. European marsh thistle prefers moist soils:
- typically grows 2 to 7 feet tall
- alternate leaves with deeply pinnate segments that have spiny teeth along leaf margins
- purple colored, disk shaped flowers, covered in spines
- often found with multiple flowers per stem
- wind dispersed seeds carried by clusters of cotton-like fuzz
European marsh thistle is distinguished from Canada thistle by having spines that cover the stem, leaves, and flowers.
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KISMA Management Practices
European marsh thistle can colonize areas quite aggressively and can be difficult to remove from areas due to their wet soils. Current management practices:
- annually hand pull or dig around rosettes
- if thistle has bloomed, clip off flowers, buds, and fruiting bodies to prevent seed production
- mow population before flower buds open when possible
- be sure to dispose of clippings in a bag
Note: It is important to pull second growth plants to eventually exhaust the seed source and deplete populations. It is also important to bag flower clippings to prevent further seed production and spread.
Species such as native swamp thistle (Cirsium muticum), swamp milkweed (Asclepias incarnata), and Joe Pye weed (Eutrochium purpureum), are all great alternatives to European marsh thistle. These species are tall herbaceous perennial flowers that are extremely similar to European marsh thistle. All of these would be great choices for replanting in areas where European marsh thistle has been removed.