Washington: Exoplanets with two suns may have trees and shrubs that are black or grey instead of the more familiar green, according to a new study.
It also suggested that flora that would appear black or grey to human eyes could have evolved on planets orbiting dim "red dwarf" stars.
This would enable plants to absorb more light to photosynthesise, using their star``s light to convert carbon dioxide into organic compounds.
Jack O``Malley-James, a PhD student and astrobiologist at St Andrews University, focused on multiple star systems thought to be common throughout the universe.
He used models for star systems with two or three stars with various combinations of Sun-like and red dwarf stars. He then added planets to these models, orbiting around one or more of the stars.
Flora on those planets would have to adapt to very different light conditions in order to photosynthesise.
"The temperature of a star determines its colour and, hence, the colour of light used for photosynthesis. Depending on the colours of their starlight, plants would evolve very differently," said James.
If a planet``s light source comes primarily from a red dwarf, then the researcher believes any possible plant life could be black or grey.
"Plants with dim red dwarf suns, for example, may appear black to our eyes, absorbing across the entire visible wavelength range in order to use as much of the available light as possible," said James.
The study was presented at the National Astronomy Meeting in Llandudno, Wales.