What's Geotropism (P&N) & What happens when a plant is placed horizontally?

A response to the stimulus of gravity. - Stem growing against force of gravity - negative geotropism - Root growing in the direction of the force of gravity - positive geotropism In a plant placed horizontally: bottom of the root contains more auxin ∴ grows less ∴ the root grows in the direction of gravity, bottom of stem contains more auxin ∴ grows more ∴ stem grows upwards against gravity