The Sunday Challenge of 2 weeks ago was : Cracks with flowers or weeds growing in them.

The wall outside of our house grows all sorts of things including plants that one would pay money for, including this one (G. palmatum), Verbena bonariensis, Linaria. purpurea, small ferns, and once we even had an oak tree trying to put down roots in a crack in the wall. We had to stop that happening.