Why are plants green?

This is a frequently posed question, that has no unique or simple answer. Prof. Lars Olof Björn has written a section on this in his book Photobiology: the science of life and light which is much more detailed than this short post. The problem with this question is that its meaning can be different to different persons. I will start by separating different aspects of this question into separate, and better-defined, questions that are easier to answer: Continue reading