Cirsium palustre, the marsh
thistle, is a herbaceous
biennial (or often
perennial) flowering plant in the family
Asteraceae. It is native to Europe, where it is particularly common on damp ground such as marshes, wet fields, moorland and beside streams. In Canada and the northern United States it is an
introduced species that has become
invasive. It grows in dense thickets that can crowd out slower growing native plants. Cirsium palustre can reach up to 2 metres (7 ft) in height and features strong stems with few branches which are covered in small spines. In its first year the plant grows as a dense
rosette and in subsequent years a candelabra of dark purple or occasionally white flowers, 10–20 millimetres (0.4–0.8 in) with purple-tipped
bracts. In the northern hemisphere these are produced from June to September. The plant provides an important source of nectar for
pollinators. This C. palustre flower was photographed in
Niitvälja, Estonia.Photograph credit:
Ivar Leidus
.gif)
