Using laser-powered microphones, scientists in Germany determined that plants and trees release gases when they perceive themselves to be under attack. These gases, in turn, produce sound waves that register on a level inaudible to anything but the most sensitive machines. The scientists, at the Institute of Applied Physics at the University of Bonn, suggested that flowers emit a whine when their leaves are cut, and that trees can warn each other of approaching swarms of insects, and that
