By Clark Brenzil PAg., Provincial Specialist Weed Control
Many questions have come to the Ministry of Agriculture’s offices about the plant in Picture 1 this spring, in response to large numbers of the weed occurring in certain areas. No need to panic! It is marsh ragwort (Senecio congestus L.), a native plant that is typically found in association with water bodies.
Marsh ragwort is a native annual, biennial or, rarely, a short-lived perennial plant in the sunflower family. It has stout, hollow stems that can get to about three to four feet high. Its leaves are broad, wavy and attached directly to the stem. The leaves taper to a point from the broad base to a narrow tip and can be somewhat lobed or coarsely serrated. Where the leaves attach to the stem, the edge of the leaf continues down the stem to create a wavy ridge along the stem.
The flowers are yellow with large, slightly darker yellow-orange disks or buttons inside a ring of ray petals. They are mainly borne in a cluster at the top of stems with a few forming in the axils of the upper leaves of the plant. Eventually the plant will produce seeds with fine hairs that help with dispersion. The majority of the seeds are relatively short-lived in the soil.
Marsh ragwort, as the name suggests, likes to grow in saturated soils surrounding water bodies. It is not poisonous and is reported as being edible, with some adventurous souls making salads and sauerkraut from it.
Because of its strong association with water, little if any research has been done on the management of marsh ragwort with herbicides. Given that it rarely spreads beyond the wetland area, herbicide management is not a high priority, and the plants can be left unmanaged without fear that it will spread to agronomic areas. The likely reason for its prevalence this year is the receding of water bodies that leave little competition for the plant, as well as a large seed bank reserve in those formerly water-covered areas that are now uncovered.
So when you see marsh ragwort, there is no need to panic and take aggressive steps to attempt control. Who knows, you may come to appreciate the rough-and-tumble appearance of this plant as a symbol of healthy wetlands.