Last May the Ash tree in our back yard flowered, then the little flowers fell to the ground. I noticed that these little flowers looked exactly like scale bushes, so I set a few on the layout to see. They looked like prototype brush and even have a little bark base so to set upright.
The Ash tree flowers on the layout from last year have lost some of their green and have dried out, they will be replaced with a fresh crop this May. I never glue anything down to the layout surface other than track, ballast and dirt for the cleaning reason. An automotive 12V mini-vacuum conneced to track DC power is uesd to pick up the old Ash Flowers along with dust. This years Spring cleaning had been started even before the flowers have fallen.