Q: I was glad to see the identification of dogfennel in your email newsletter. The foliage smells like the herb fennel. Is dogfennel edible?

A: My general rule is that if cows won’t eat a plant, I won’t eat that plant. As I wrote, cows avoid dogfennel, Eupatorium capillifolium; it makes their milk taste bad if they accidentally munch on it. Although Joe Pye weed, Eupatorium purpureum, has been used as an herbal medicine, white snakeroot, Eupatorium rugosum, is poisonous to livestock. My advice is to cook with fennel you buy at a grocery.