We have three varieties in my yard, and my guide today to the relative potency is Louie. Catnip, or Nepeta cataria, is the least favored, although it seeds itself well and we now have several established locations. I also have two species of catmint, although I do not know for sure which species they are. One is larger and has quite lovely blue flowers. The cats' favorite, however, is the smallest plant. It nearly didn't make it through spring for being rolled on, so it is recovering under a pot holder.