which is green
http://en.wikipedia.org/wiki/Light#mediaviewer/File:Linear_v...
That is why grass/trees are green - they consume only the edges of the spectrum (about 10-15% of the total sunlight coming through) bouncing the rest back.
With respect to the original point about orange being average color of Internet photos - keep in mind that most photos are produced by digital CCD cameras which are more sensitive to orange/red than green/blue.
There's no real consensus on why. (There's some wild guessing that green photons might be too hot to handle: smashing fragile biomolecules apart rather than powering them... (http://scienceline.ucsb.edu/getkey.php?key=500) but then why does chlorophyll run fine on purple light?) You'd figure that there would be incredible selection pressure on increasing photosynthesis efficiency, but maybe they're stuck on a local maxima: it's not like a single mutation can turn a C3 plant into a C4 plant: http://en.wikipedia.org/wiki/C4_photosynthesis
the plants consume edges of spectrum, so they would bounce the X wavelengths (green in case of our Earth) as it is just an unnecessary heat for them.
