It is hard to ignore plants with leaves as stunning as these in a Parks garden. The purple is from one of the Sumachs or Rhus family. Selecting plants that contrast in colour shape or form is part of the skill of gardening but starting with plants like these is a good beginning.
Purple is one of my favourite leaf colours of the moment and the Lamium below is called Perilla fructenscens. I am putting several plants in one area of my garden and will see how well they get on with one another.
This Heuchera surprised me growing in a wall cleft with thin soil. I do not remember planting it in what I thought would be a hostile location.