Not a silly question at all. I only have real knowledge of the medicinal properties of A.millefolium. It seemed to be the one that grew fairly freely in the mountains. There are several varieties of it now, but I still think most teas are made from millefolium.
I also meant to respond to your kitty note; I've had a cat or two for maybe 30 years and suddenly now for a year I have a rescued dog. A big dog that I absolutely adore. Her name is Sunshine, no particular ancestry at all. Just a dog from the shelter.
But . . . yarrow, I only know for sure about A.millefolium.
