My mother grew this in the rock walls of the patio. It survived purely on the moisture retained in the stones. Not hardy in zone 6, it self-seeds happily when conditions are right: dappled shade, moisture. It is Cymbalaria muralis, a sweetly descriptive plant name.
I pulled some cuttings before she died. These are like the Johnny jump-ups. They go where they please, and I don't try to regulate location, size, or spread. They are a link to my origins and memories.