I'm not saying the science is settled, but:
Researchers from the University of Missouri found plants respond to attack. They discovered the sound of caterpillars eating made them more defensive. Plants that heard caterpillar sounds released more mustard oils, which are unappealing to caterpillars and thus ward them off.
I'm going to write a ballad,
about a tragic salad.
Lettuce hope you hear the call,
because some don't carrot all.