We have comfrey (knitbone) growing in the front yard. I forget how it got there (if I ever knew). Ailz suggests every once in a while that I should grub it out and I always refuse. I like wild flowers. Comfrey has a thick hairy stalk, thick leaves and tiny little pinky-purple flower bells. It draws the bees. This year, thanks to all the rain, the strongest plant is nearly as tall as I am.