European Marsh Water Thistle


Invasive - Eradicate!

European Water Thistle has no known direct food value to wildlife and is considered an invasive species. Other names for this plant include: March Thistle, Swamp Thistle & Marsh Plume Thistle.



Once introduced, European Marsh Thistle aggressively colonizes natural areas, decreases biodiversity and compromises the ecological integrity of an area.

Plant Description:

European Marsh Thistle is an herbaceous biennial that grows 4 to 5 feet in height. European Marsh Thistle is found primarily in moist areas, near rivers and by ponds. Leaves in first-year rosettes are spiny, long, deeply lobed and hairy on the underside. On flowering plants, leaves are 6 to 8 inches long near the base and shorter toward the top.

Hints to Identify

European Marsh Thistle forms a spiny rosette consisting of a circle of leaves close ground (pictured on the right in the photo below).

Homeowner Treatment Options
Shore - Klear
*Aquatic Biologists recommends implementing preventative management techniques and physical removal prior to, or in conjunction with treatment.


Common Application Questions

Q. How much should I treat?

A. The entire population should be treated as European Marsh Thistle is an extremely invasive species.

Q. When is the best time to treat?

A. Once water temperatures are around sixty degrees or warmer.

Q. How long before I see results?

A. It really depends on the product you choose. For most vegetation, control will take approximately 2 weeks however, tissue damage may be evident within 2 to 4 days with liquid formulations. Some products are slower acting with results taking 30 days or more to achieve.