As strong and durable as tabby is, it is perpetually vulnerable to vegetation that so easily finds a foothold on its rough texture, and organic composition. This is the only plant I've seen on any of the walls, and I'm loathe to report it to the rangers, or tear it out myself. I don't think this one little guy will do any harm as long as he doesn't make friends with any newcomers. I want to photograph it again in different light, but I had to be sure I had at least this one lest it be gone when I visit again.
Update: I have replaced the photograph I posted with this one that is better I think.