Trees may appear stationary, but new research shows they have a sophisticated way of monitoring their own physical shape and correcting it.

Scientists from INRAE and the University Clermont Auvergne have found that young trees can sense when their stems are curved and alter the formation of specialised wood to gradually straighten themselves. The finding provides new evidence for tree proprioception, the ability of plants to perceive the position and shape of their own bodies.

The study, published in New Phytologist, examines how young poplar trees respond to changes in stem curvature without relying on the usual environmental signals of gravity and directional light.

What is tree proprioception?

Proprioception is commonly associated with animals. It allows the body to recognise the position of its limbs and coordinate muscles to maintain posture and movement.

Scientists had long questioned whether plants could perform a comparable function. Research published by an INRAE team in 2012 provided evidence that plants could perceive their own shape and use that information to regulate posture.

The latest research offers more detail about how this process works in young trees.

The researchers focused on tension wood, a specialised type of wood that develops in response to stem curvature and generates forces capable of changing the direction in which a stem grows.

Scientists removed gravity and light cues

Studying the tree's ability to sense its own shape required researchers to eliminate other signals that normally influence growth.

Young poplar trees were placed horizontally, where they initially responded by growing upwards. Tension wood formed on the upper side of their stems and generated forces that helped move the stems towards a vertical position.

After the trees reached the desired curvature, roughly 10 days later, researchers transferred them into a specially designed experimental setup.

The apparatus consisted of a horizontal platform rotating around its own axis inside a uniformly illuminated sphere. Because light reached the trees equally from every direction and the experimental conditions removed the normal directional effects of gravity, the researchers were able to focus on the trees' response to their own curvature.

Tension wood works in opposite directions

The researchers observed a change in how tension wood developed after the trees had reached their initial position.

The tension wood that had previously formed on the upper side of the stem stopped developing. Instead, specialised wood began forming on the opposite side.

Over the following weeks, the stems gradually became straighter.

The results suggest that trees can use tension wood in opposing directions, producing forces that first correct one type of curvature and later counteract it when the stem moves too far from the desired position.

This resembles the principle of opposing muscles in animals, although the biological mechanisms are fundamentally different.

The discovery also challenges the assumption that tension wood is produced only on the upper side of a leaning stem.

How trees maintain their balance

The research indicates that trees do not simply react to external signals such as gravity and light. They can also gather information about their own physical structure and use it to regulate growth.

This feedback system could help trees respond after disturbances such as strong storms, landslides or other events that alter their posture.

By changing where specialised wood develops, a tree may gradually adjust its structure and regain a more stable position.

The process is regulated at the cellular level, with the tree's perception of its own curvature influencing where tension wood is produced.

Potential uses in farming and forestry

Understanding how plants sense and correct their own shape could have applications beyond basic plant science.

Researchers suggest that a better understanding of plant proprioception could eventually help in developing crops with stronger or more upright growth patterns. Such traits could reduce lodging, a problem in which cereal crops bend or fall over.

The findings may also be relevant to forestry. The way trees produce internal stresses as they respond to changes in posture can affect wood development and quality.

For scientists, the study provides a closer look at how plants coordinate growth without a nervous system or muscles. A tree's ability to detect its own curvature and alter tissue formation shows that maintaining stability involves an active biological feedback process, even in organisms that remain rooted in one place.