Prickly comfrey is an Old World plant that has occasionally been used for herbal medicine. In Finland, you would be consuming a tincture of tarharaunioyrtti, or pikkusormustinkukka; in Sweden it might be fodervallort. Fascinating language. Almost makes them sound like chemists. A chemist would say you're taking pyrrolizidine alkaloids, and tell you to stop! Turns out comfrey is toxic to our livers, particularly if you're an adult male. Don't know why females and young catch a little bit of a break. Comfrey is also toxic to herbivores. But it must be good for something? Butterflies! Some caterpillars eat it, sequester the alkaloids, pass it to adults, and they all become less likely to be eaten. Rough comfrey grows in AK, CA, CT, MA, MD, ME, MI, MN, NY, OH, OR, VT, WA, WI, BC, MB, NB, NF, NS, ON, PC, QC, and SK. Lenawee Co MI, 5/24/12. Borage family, Boraginaceae.