Pineapple mint has taken over and has set up beach heads in several debris clumps.  Debris clumps are gatherings of old discarded potting mix and plant carcasses left on the roof surface to support whatever it is that can grow in that environment.  These have been discussed here in previous years.  Last year these clumps didn’t fare too well due to drought conditions.  I typically do not water them nor do  I seed them.  Whatever grows in them happens by sheer accident.  More of these will be shown as the season progresses.  The building in the background is a new feature this year.