Flora that would appear black or grey to human eyes could have evolved on planets orbiting dim "red dwarf" stars, according to unpublished research that is being presented at the National Astronomy Meeting in Llandudno, Wales.
This would enable plants to absorb more light to photosynthesise, using their star's light to convert carbon dioxide into organic compounds.
(whole story here)
It's good to be reminded that we consider the "visible" portion of the electromagnetic spectrum (red-violet) is entirely a function of our visual systems, and the selection pressure under which they evolved (particularly the ability to see well in the green band, the middle of our range) which is itself entirely a function of the particular light output of our particular sun in this remote portion of our particular galaxy.
Life evolving under a different sun could have photosynthetic organisms optimized to extract energy from a different part of the spectrum, and creatures with visual systems tuned to the corresponding "colors". And really, I only put "colors" in quotes because we would be unable to experience them as colors; those organisms would experience them as colors that we are literally incapable of even imagining.
I'm sure there's a metaphor here, but I forgot what it is.