There's this one really creepy episode of Doctor Who that had cybernetic trees that also served as light sources. It was a major plot point that protected the heroes from the Monsters-of-the-Week. While we may not be under threat from psychopathic angel assassins/statues, Taiwanese scientists are working on giving trees the same ethereal glow seen on that popular British science fiction series.
Dr. Yen Hsun Su and his team discovered that infusing Bacopa caroliniana tree leaves with gold nanoparticles caused them to emit a luminous red glow. The effect is generated by exposing the trees to ultraviolet light. The implanted nanoparticles react to the UV, which in turn stimulate the leaves' chlorophyll into bioluminescence. The whole process also sends the trees into photosynthesis, capturing more carbon from the atmosphere.
This happy accident came about during their experiments to create an eco-friendly alternative to LEDs, which contain toxic phosphor powder. The breakthrough has a host of future applications, such as using trees to replace street lamps, and of course for staving off time-displacing sociopaths disguised as angelic stonework.