I have only been hunting ginseng for 5 years now, but the very first patch that I found has 2 very nice plants that were undiggable. One was at the very top of a rocky ridge, and had grown into the root of a red oak that is perched atop the ridge. The other has grown down into a crack in the ledge. It has pancaked itself onto the 3/4\" crack. I did not think to take photos when I planted the seeds last week but both plants are very nice 4 prongs.
Just wondered if there were others that have plants that can not be dug.
Good Luck
Sargie