A tree knocked sideways by a storm can still end up growing upright, and French researchers have now shown how. The study, by scientists at INRAE, the French national research institute, and Université Clermont Auvergne, was published in New Phytologist on 2 September 2026. It found that trees sense their own shape and grow a special kind of wood to correct it.
To follow the experiment, it helps to know what tension wood is. INRAE says it acts like a muscle: on the upper side of a stem it contracts and pulls the stem upward. Before this study, it was thought to form only on the upper side. The experiment began with young poplar trees laid horizontally. Over about ten days their stems curved upward until their tops were vertical. That raised a question: do trees only react to gravity and light, or do they also sense their own bend?
To separate those cues, the researchers moved the trees onto a clinostat, a horizontal platform rotating inside a sphere lit from all directions, which removed steady gravity and light signals. In that setup, tension wood on the upper side stopped forming, and identical wood formed on the opposite side, acting as an opposing muscle that pulled in the reverse direction. The opposing forces gradually straightened the stems over several weeks.
The finding also answers an old puzzle. INRAE says plants use proprioception to control their posture and stay as straight as possible, but the biological mechanism behind it was unknown until this study. Tension wood can be seen at the base of trees on mountain slopes. Its formation is a complex, cell-regulated process with several stages, and proprioception governs it. Félix Hartmann, an INRAE research engineer, said revealing the remarkable capabilities of trees requires a great deal of ingenuity.
The researchers say this shows trees use proprioception, an internal sense of their own shape, to decide where tension wood forms. Proprioception means perceiving the position of one’s own body parts, and it was long thought to exist only in animals; a 2012 study involving INRAE showed plants have it too. Bruno Moulia, INRAE research director, said the team had uncovered “a genuine sensorimotor loop” operating in the woody parts of trees.
The authors suggest uses in forests and fields. The findings may help explain how trees stay resilient after storms or landslides. Breeding crops for proprioception could favour plants that stay upright, which could reduce lodging, the term for crops falling flat near the end of the season and causing yield losses. INRAE also says poor coordination of tension wood activation can create excessive internal stress, which affects wood quality.
Scientists in France studied young trees called poplars. When the trees were laid on their sides, they grew upward again.
They grew a special wood on the upper side of the stem. It pulled the stem up. Even when light and gravity cues were removed, the trees grew this wood and straightened.
The scientists say trees can sense their own shape. This might help grow straighter trees.