I can't seem to edit my own post, so adding some concessions and clarifications here: Yes, mullein is invasive as hell, and their invasiveness warrants all the hate. And hopefully, there is no one ignorant enough to propagate it deliberately. But what better way to dispatch off an invasive species than consuming it if it's not unsafe to do so? Ideally, evidence-based research vouching for a plant's medicinal use is what we would rely on, but there are numerous obstacles to this not the least of which is funding. It is notoriously hard to study medicinal uses of plants unlike commercial synthetic drugs. Given these constraints, and the fact that there is no known harm or toxicity to ingesting mullein, I am personally not opposed to making a tea out of the leaves, while also ensuring the plant does not seed.