In the past, I have had to cut neglected fields that were overgrown with this plant. It was taller than I was! You've probably seen this plant along fence lines and roadways. I am not one of the people who likes the way it smells.
Its name is dog fennel. It is not the same fennel used in kitchens. The two plants are not even in the same family. The kitchen herb is in the carrot family. The dog fennel is related to daisies and sunflowers. I would not take dog fennel internally because it has alkaloids that can damage the liver. Livestock won't eat it.
A Native American tribe in North Carolina did take internal preparations of dog fennel, but I am not comfortable sharing that information. Some people do eat small quantities of it in dishes and claim it has not affected their health. Seeing as to how there are plenty of other plants we can safely consume, so why risk it?
Dog fennel has antifungal properties. The fresh leaves can be crushed and used externally on wounds and insect stings. You could make a tea to use as an antifungal wash.
Dog fennel is also useful to us as an insect repellent.* Native Americans burned fresh stalks on their fires to ward off mosquitoes. It can be cut and laid in bundles inside dog houses and dog runs to repel ticks and mosquitoes. Some pick the green stalks, crush the leaves, and rub them on their skin to repel mosquitoes and biting flies.
I've been told that the best way to use it as an insect repellent is to make a spray from the extracted oils. You should research it to learn more about extracting, but here are some very brief instructions to illustrate how simple the process can be. You can extract the oils by stuffing a pot with fresh, bruised plants, covering them with water, applying gentle heat for several hours. Then you strain off the plant matter and bottle with 10-20% carrier oil. The carrier oil helps stabilize the plant extracts making hold potency last longer. It seems to give 1.5-4 hours of protection depending on strong the extracted liquid is and how hot it is. Growing conditions, when you pick it, how tightly you pack your pot, etc all will affect the strength.
After the plant has dried naturally in the field, the leaves and stalks make good fire tinder. I use the dried stalks to mark planted rows in my garden. I read that Native Americans used the stalks as shafts for arrows. If true, those arrows must have been used for lightweight purposes as the dried shafts are hollow and brittle. They will split and break into fairly easily. I can push them into loose soil, but they snap when I try to push them into harder packed soil. Maybe they hardened them with heat at a certain time.
*The dog-fennel oil was more potent than the conventional insecticide malathion. In conclusion, these combined results showed Eupatorium capillifolium oil is a promising novel source of a biological insecticide with multiple modes of action. source
