Marsh Plume Thistle
ALERT SPP This Plant is on high alert.
Latin Name: Cirsium palustre
Physical Description: It’s a biennial herb from a fibrous root. The stems are single, erect, slender, ribbed with simple or sometimes ascending branches above. The stems are strongly spiny-winged and can grow up to 2.0 m tall. The leaves are spiny and hairy. Flowers are found in a dense cluster at the end of stems. They are often dark purple to lavender in colour. The flower heads have green to purple-tinged bracts that covered in cobwebby hairs. The outer bracts are often sticky.
Habitat: It prefers wet soils and is well adapted to sand, sandy clay and clay soil textures. It can be found in moist woodlands and meadows, riparian areas and along roadsides.
Impacts: It can supress growth of native/desirable vegetation reducing biodiversity. It can form dense monocultures and can impede movement of livestock and wildlife because of its spiny nature. It can impact forestry operations and forest regeneration as it can form dense clumps in cut blocks, competing for moisture and nutrients with tree seedlings.
Reproduction: It reproduces by seed and can be dispersed by wind, water and through soil movement. Each individual plant can produce up to 2,000 seeds.
Mechanical: Where infestations are small, plants can be removed through hand-pulling or mowing. If plants are removed when flowers are absent, the plants can be left on site to decompose. If the plants are removed while flowers then flower heads must be carefully bagged and disposed of properly.
Chemical: Several herbicides with the following active ingredients can control Marsh plume thistle: clopyralid, aminopyralid and metsulfuron-methyl. For available products, contact your local agri-supply store. Prior to any herbicide application, read and follow the label instructions
Biological: Rhinocyllus conicus is a seed feeding beetle that has been released in B.C. but is still under study as a treatment tool. It is currently not available for general distribution.
Alberta Invasive Species Council. Rush Skeletonweed. Fact Sheet.