Scientists are conducting studies on trees to determine how water moves through trees. Many believe trees passively draw water into their system as leaves become thirsty. New research shows trees may have a pulse. A tree’s pulse stretches over hours slow and steady. Researchers scanned 22 trees at night with a laser to senses any movement. The trees were located in a greenhouse with only the moon as light. Scientists observed movement from one half centimeter up to a full nine centimeters at the crown. Scientists believe this is an unknown pumping mechanism requiring further study.