FreeGameDev

I know many of you are just dying to start modelling alien worlds and I have been meaning to start a discussion about it for a while. I will add links to useful resources as I find them.

So starting with plants: This page has information about how alien plant life may look: http://solstation.com/life/a-plants.htm
So looks like its basic black for plants on low light worlds.

Plant-like life forms under a bluer and brighter star than the Sun may reflect the less useful or abundant red and yellow
light, so appearing in autumn tones.

The latest release of Stunt Rally, the cool open source racing game that just had a release, has just what you might be looking for! Check out the extreme difficulty tracks. They are prefixed with 'X' and coloured in purple. You might even be able to take a texture or two from Stunt Rally, but keep in mind they're not all freely licensed (but most are).

They're not "realistic" of course and their appearance has no scientific basis, unlike what you linked to. Still, they could be some help in determining what the surface of another planet could look like in a game (and not a simulation game at that... cooler is better).