The euaclyptus trees are such a vivid blue-green that, en masse, they turn the mountains and sky around it blue. See it for yourself in the Blue Mountains outside of Sydney, Australia. Place a piece of it in your home with this swishy branch.
 
I offer this painting in archival Hahnemuhle photo rag, a fine art paper that will not fade with time. Pictured with "Blue Mountain Eucalyptus II" in the second photo.