Although its flowers resemble daisies, the leaves and strong odor of dog fennel (Anthemis cotula) make identification easy.
Dog fennel is a native of Europe which now occurs worldwide. Adapting easily to many different growing conditions, this annual can be found in waste areas, barnyards, overgrazed fields and cultivated fields. Because of dog fennel’s tendency to invade cultivated areas it is classified as a noxious weed.
Known by many common names, including mayweed, wild daisy, mayweed chamomile and stinking fennel, dog fennel is a bushy plant with a short taproot that grows from a half to three feet in height. The alternate leaves are deeply divided two or three times into narrow segments, giving the stalkless leaves a lacy appearance. Dog fennel’s many flowers are borne at the top of the well-branches stem and in leaf axils. Ten to twenty creamy white ray flowers (petals) encircle bright yellow disk flowers (the center) to form the daily-like flowers. The white ray flowers are toothed at the tips. Dog fennel seeds, the plants’ method of spreading, are achenes (dry, one-seeded fruits) that do not have a pappus (hairs or bristles on top). When crushed dog fennel has a strong odor that is usually described as ill-smelling, although I do not think its aroma is foul.
The plants is considered of no value. Dog fennel can cause contact dermatitis when touched. Animals that eat dog fennel can get blisters on their skin or muzzles and irritation to the mucous membranes. The milk of dairy animals that eat dog fennel has a strong flavor. Some references suggest that a tea made from dog fennel can be used for colds, asthma, rheumatism or epilepsy. I personally would not ingest a tea made from a plant that can cause skin and mucous membrane blistering, no matter how bad my cold.
The scientific name derives from Greek: “anthemon” means “flower” and was designated as the genus because dog fennel blooms profusely while the species name (“kotule” means “cup”) describes the cup shape of the flower or perhaps the hollow at the base of the leaf where it attaches to the stem.
These dog fennel plants were photographed late last summer along the Tule River in Shasta County CA.