Scientists in Germany made a mold of the surface of rose petals and used it to cast a transparent surface for solar cells that absorbs light better than traditional surfaces.
Researchers “investigated the optical properties, and above all, the antireflection effect of the epidermal cells of different plant species. These properties are particularly pronounced in rose petals where they provide stronger color contrasts and thus increase the chance of pollination.”
“Scientists reproduced the epidermal cells of rose petals that have particularly good antireflection properties and integrated the transparent replicas into an organic solar cell. This resulted in a relative efficiency gain of twelve percent.”
It is possible that dark-colored roses are dark partly because their petals have more antireflective surfaces than lighter roses, in addition to whatever pigments they contain.