2015 is the International Year of Light, a year designated by the United Nations to appreciate and learn about optical phenomena. To launch their celebrations, the Perimeter Institute for Theoretical Physics illustrated 20 of their favourite light facts.
The "plants are green..." one is very easy for people to mess up. Amusingly, in Caliban's War, the authors did a pretty good job of portraying the botanist character, except one big goof when he's describing the lighting as a thin, pink spectrum that would "kill any plants left under it in less than a week".
Apparently they haven't read all those articles on vertical farms using pinkish LEDs, because that's actually what the best grow lights look like to the human eye. Ooops.