Anthemis cotula (Dog Fennel)
|Also known as:||Stinking Chamomile, Mayweed|
|Habitat:||sun; disturned soil; roadsides, gravel pits, clearings, agricultural fields|
|Bloom season:||June - September|
|Plant height:||6 to 24 inches|
|Wetland Indicator Status:||GP: FACU MW: FACU NCNE: FACU|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Daisy-type flowers, single at the tips of branching stems. Flowers are 2/3 to 1¼ inches across with 10 to 16 white petals (ray flowers) with 3 small teeth at the tip, and a golden yellow center disk that expands from button-shaped to dome-shaped to nearly round as it matures.
The bracts surrounding the base of the flower are in 2 or 3 layers, narrowly lance-linear to triangular, green with a wide band of pale, membranous edging and covered in long, bent or cobwebby hairs. Flower stalks are slender, hairless to sparsely hairy.
Leaves and stems:
Leaves are alternate, 1 to 2½ inches long, up to 1¼ wide, 1 or 2 times pinnately lobed with short, linear, sharply pointed segments, and short-stalked to stalkless. Surfaces are hairless to sparsely hairy and have an unpleasant odor when crushed. Leaves are mostly alternate with the lowest leaves opposite. Stems are usually erect, much branched, hairless to sparsely hairy, green or tinged red, and gland-dotted.
The center disk becomes a round head of dry, dark brown seeds that lack a tuft of hairs. Seeds are ribbed and covered in small protrusions (tubercules) and often gland-dotted.
A weed introduced from Eurasia, Dog Fennel is now widespread in North America and found sporadically across Minnesota, mostly along roadsides and farm fields. It is allelopathic, releasing chemicals that inhibit the growth of competing plants and allow it to form dense colonies. Similar to the also-weedy Matricaria and Tripleurospermum species, the unpleasantly smelly leaves are a good distinguishing characteristic. The leaf segments of Anthemis are also pinnately lobed (divisions on opposite sides of the common stalk) where the other 2 species have branching segments with the lobes more thread-like.
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Photos courtesy Peter M. Dziuk taken in Aitkin and Dodge counties.
Have you seen this plant in Minnesota, or have any other comments about it?