Well, Elite is Sci-Fi, even thou it is pretty authentic i terms of science, but still a Sci-Fi.
With that I completely concur - and admit it is quite the challenge to convey tone and inflection in a forum without writing in phonetics and dialectical marks, which then looks like a strange, alien dialect.
But being that Elite tries to lean more towards the science and a bit less towards the fiction, I find it unlikely we'll see too much in the lines of pastel seas of alien flora.
Granted there are these things:

And they are most certainly not green, but then they also grow in places without atmospheres, and to the best of my knowledge no where near approach what could be mistaken for a forest.
And while tree-like probably have less in common with a tree and more in common with some manner of myconid growth.
But as we lack the in-game tools to actually carry out any sort of actual research, or even a means to take a sample of such things to someone who could put it under a microscope, mass spectrometer, gas chromatograph or even give it a rub, taste, chew test, we're left to speculate at best.