Although these four plants are probably pleasant, docile additions to the garden in the appropriate environment, they were the menacing bullies of my herb garden. The catnip was the most aggressive, and right behind it was the oregano. I planted the first because someone told me the hummingbirds would like it. It overwhelmed one half of the herb garden and I haven't seen a hummingbird near it yet. The oregano was a nice looking little clump that just fit in a bare spot, then it turned into the monster that ate my Russian Sage.
The other two plants are parsley, and something else that kind of looks like the oregano plant. It grows the same anyway - too much. The parsley is just ugly.
I didn't want to just kill them so I moved them to the fringe of the pond. Far enough away that they can't feed on the pond run-off, but close enough that I will occasionally water them.