A flowering plant might not be able to tell how many fingers you’re holding up, but it can tell whether it’s light or dark outside and might grow differently if it suddenly finds itself in the shade of another plant.
Plants do that through photoreceptors, which are a major focus of research for John Clark Lagarias, a distinguished professor emeritus of molecular and cellular biology.
Photoreceptors have important uses, like measuring the length of the day; plants can tell when seasons change because the days get longer or shorter.
