True color of leaves

[Ray Atchinson]

I heard on a recent public radio show that leaves don't 'turn' colors
in the fall - that the fall colors are their true colors.  They are green
only due to photosynthesis.  Now, I don't want to become an expert, or
engage in word games if this is what it is - but I'd like to know:
Are leaves green, and turn colors in the fall, or are leaves colors and only 
green in the summer?  (in case you're wondering, yes, I am serious - a brief 
comment or text reference will help me.  Seems I quoted the radio show to a 
friend who now thinks I'm pulling her leg.)

Thnks