Trees have a remarkable ability to sense their own shape and adjust their growth to stay upright. This awareness of body position, known as proprioception, was once thought to exist only in animals. However, in 2012, researchers working with INRAE demonstrated that plants also possess this ability (Bastien R. et al., PNAS).
This internal sense allows plants to monitor their posture and make adjustments that help them grow as straight as possible (Moulia et al., Science). Although scientists had established that plants could detect their own shape, the biological processes responsible for turning that information into physical movement remained a mystery. How Scientists Isolated Trees' Hidden Sense Plants use several kinds of information to guide their growth.
They respond to gravity, detect the direction of sunlight, and monitor the shape and position of their own stems. To understand how this internal sense works independently, researchers needed to eliminate the directional signals provided by gravity and light. They developed an unusual experimental system designed to isolate proprioception.
Young trees were placed on a horizontal platform that rotated around its axis inside a sphere illuminated equally from every direction. The rotating platform prevented the trees from receiving a consistent directional signal from gravity, while the surrounding light eliminated cues about which way they should grow. This arrangement allowed the researchers to investigate how trees respond to their own shape without relying on the usual environmental signals that influence their growth.
The Muscle-Like Wood That Helps Trees Straighten Themselves The experiment began with young poplar trees positioned horizontally. As the trees grew, their stems gradually curved upward, bringing their tops back toward a vertical position. This response depends on a specialized type of wood called tension wood.
Unlike ordinary wood, tension wood can generate pulling forces as it develops. When it forms along the upper side of a stem, it acts much like a contracting muscle, pulling the stem upward and causing it to bend. After approximately ten days, once the trees had developed a noticeable curve, researchers moved them into the experimental apparatus.
Extract — continue reading at the source.
