<u>Integration of applied force by bean stems determines initiation of twining behavior around supporting structures: </u>

Twining plants do not rely on self-supporting structural integrity to uphold their weight while growing away from gravity and toward a light source. Instead, twining plants rely on external stable structures to hold their weight by twining around them.
An important phase in successfully attaching to such a supporting structure depends on the plant choosing a suitable support.
The plant will move in a periodic circular motion called circumnutation, attempting to collide with potential supports. If a collision occurs, the plant either twines around it or not. Our study suggests that this decision is determined by an integration of the force applied on the plant during contact with the support, a force that is driven by the circumnutational movement.
When the accumulated force does not pass a critical level, the stem will tend to 'slip' off of the support and continue the circumnutation 'search' behavior.
Such behavior acts as a filter for what structures are stable enough to support the plant and is a major evolutionary advantage over similar twining plants with no or less effective filters, resulting in a higher probability of collapse whilst growing on non-stable supports.