A new study published in Cell today reveals that plants make sounds when they are thirsty or stressed. Researchers found that plants that need water or have been cut make up to 35 pounds per hour. On the other hand, well-watered plants make only one sound per hour. However, humans cannot hear these sounds because they are too high-pitched, between 20 and 100 kilohertz. Animals like bats, mice, and moths could potentially hear them. The study also shows that plants respond to sounds made by animals. Researchers, led by Lilach Hadany at Tel-Aviv University in Israel, studied plants by placing tobacco and tomato plants in small boxes fitted with microphones. These microphones were able to pick up sounds made by the plants, even if the sounds were not audible to humans. They discovered that plants make noises more noticeably when they are stressed, either by a lack of water or by recent cutting. Lilach Hadany describes the sounds as short clicks, similar to the sound of popcorn when pi