Earth and Sky科普英語：Plant Signals 植物的語言
Can plants smell and taste in the same way that animals do? Can they talk to each other and to insects? Learn how scientists hope to unravel some of the mysteries of plant senses -- on today's Earth and Sky.
JB: This is Earth and Sky. If an insect is damaging a plant, the plant may send out an airborne signal -- like an odor -- attracting just the right predators -- perhaps flies or wasps to attack the offending insect.
DB: Penn State entomologist Jack Schultz told us that not only can plants send chemical signals to insects -- they can send them to other plants.
Jack Schultz: If you put an unwounded plant in the presence of a wounded plant something will pass through the air -- or at least the evidence is -- that a signal will pass through the air from the wounded plant to the unwounded plant, and turn on defenses in the unwounded plant.
JB: So far, scientists can only see the effects of these chemical signals that fly through the air.
Jack Schultz: We just don't have the instrumentation or the gadgets necessary to collect those molecules outside in open air and demonstrate that Molecule A went from Plant 1 to Plant 2 or from the plant to an insect, and is the cause of the change in the behavior of the receiver organism.
DB: Schultz is working with engineers to develop devices that might one day detect the complex signals sent out and received by plants. Tomorrow -- more on plant senses and defenses. Our thanks to the National Science Foundation -- where discoveries begin. We're Block and Byrd for Earth and Sky.
