Here's the whole deal. The seeds are extremely light. Some of us remember those frustrating Boy Scout efforts to rub sticks and start fires. Once you get the hang of it, you know that you can strip a handful of these off a plant for tinder. And there's not much else horseweed is good for. The genus Conyza was long part of Erigeron with the fleabanes. Some botanists still include it there. They can determine plant relationships with impressive precision, but it's still a little dicey deciding where to draw lines between species.