Describe $(1)$ Photoperiodism.

(N/A) Photoperiodism is the physiological response of plants to the relative lengths of light and dark periods.
It is a developmental response to the duration of light exposure,which is crucial for the transition from vegetative growth to flowering.
Based on their photoperiodic requirements,plants are classified into three categories:
$1$. Long-day plants: These require a longer duration of light than a critical period to flower.
$2$. Short-day plants: These require a shorter duration of light than a critical period to flower.
$3$. Day-neutral plants: These do not show any correlation between exposure to light duration and the induction of flowering.
The site of perception of light/dark duration is the leaves,which synthesize a hormonal substance that migrates to the shoot apices to induce flowering.