LA JOLLA -- (Dec. 24, 2015) Despite seeming passive, plants wage wars with each other to outgrow and absorb sunlight. If a plant is shaded by another, it becomes cut off from essential sunlight it needs to survive.
To escape this deadly shade, plants have light sensors that can set off an internal alarm when threatened by the shade of other plants. Their sensors can detect depletion of red and blue light (wavelengths absorbed by vegetation) to distinguish between an aggressive nearby plant from a passing cloud.