Handedness in plant growth may be most familiar to us when we think of tendrils or twining plants, which generally form consistent right– or left–handed helices as they climb. The petals of several species are sometimes arranged like fan blades that twist in the same direction. 

Another less conspicuous example is ‘circumnutation’, the oscillating growth of axial organs, which alternates between a clockwise and an anti–clockwise direction. Our aim is to unravel the determinants of handedness in climbing plants.