Diagram explaining the interactions between gravitropism and phototropism in classical experiments dedicated to the study of gravitropism and phototropism.

A: In classical experiments, a plant is tilted from the vertical in order to study gravitropism. In this case, since the light is coming from the top, one side of the stem is shaded, which can induce a phototropic reaction. B: In classical experiments, a plant is lit unilaterally in order to study phototropism. Since the plant bends towards the unilateral light, the stem is curved and thus tilted, which can induce a possible counteractive movement due to gravitropism.