Weed du Jour – Common Groundsel

OK, it’s 30 degrees at noontime. There are snow flurries in the air and there’s a cold, biting wind. But believe it or not, there are three weeds in the yard that are actively growing! I’ve identified two of them and I’m close to knowing what the third one is.

Common Groundsel

Common Groundsel

The first weed du jour of 2013 is the one I’m seeing all along the edges of the yard – common groundsel (Senecio vulgaris). This plant is a member of the huge aster (Asteraceae) family  that includes dandelions, chrysanthemums, zinnias, daisies and more.

One of the problems I had in identifying this plant is the fact that it is both a winter and summer annual. A winter annual is a plant that starts to grow in the autumn and blooms in the spring. A summer annual grows in the spring and blossoms in the summer and fall. Common groundsel is both – basically it’ll grow at anytime and be ready to bloom whenever the conditions are right. The tight little rosettes of leaves with a hint of purple in them that I’m seeing now are groundsel as a winter annual. As a summer annual the plant’s larger, lighter green and less compact  The advantage of being a summer and winter annual is that groundsel can have 3-4 generations in one growing season.

The leaves of common groundsel are deeply lobed, reminding me a little of a thistle (another Asteraceae) but lacking the thorns. The plants have a small tap root with a lot of secondary fibrous roots.

Open Common Groundsel Flowers

Open Common Groundsel Flowers

The most distinctive characteristic for me is the flower of groundsel. The small yellow flowers are surrounded by green bracts. The bloom isn’t large and doesn’t look fully open even when it is. The seedheads that are produced look like a small dandelion and the seeds are scattered by the wind.

An interesting and somewhat disturbing fact is that an open flower of groundsel can develop fully viable seeds even after the plant has been killed by cultivation or an herbicide. Yikes! This means that if the plant is blossoming, don’t just hoe it up and leave it in the garden or spray it with Round Up. If you do, it’ll still produce seeds. Instead, throw any groundsel into the trash to keep from adding more of its seeds to the soil. (After learning this, I have a few groundsel plants that I need to pick up.)

Groundsel also showed up on WebMD. There is some tradition of using this weed for epilepsy and other conditions. But this can be a dangerous thing to do since this plant has pyrrolizidine alkaloids in it that can cause vascular and liver damage. Common groundsel is also a risk in pastures where horses and cattle can be affected by the chemicals in its leaves.

Common Groundsel

Common Groundsel

While this weed has truly spread like a weed in the yard, with diligent cultivation or herbicide use, it can be kept under control. Just know that common groundsel will grow and blossom throughout the growing season and will be a constant weed with which to contend. But at least now I know what it is!


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