SIGMOID CURVE/ GROWTH CURVE: A plant exhibit differential growth during its life cycle. In the case of herbaceous plants, the growth is exhibited in three steps, i.e. lag phase, log phase, and phase.

Lag phase: It refers to the first stage of the life cycle of a plant. In this stage, the growth is negligible. 

Log phase: During the log phase, the plant exhibits logarithmic in the size. It is the phase, in which maximum growth is seen.

Steady phase: During the steady phase growth ceases, and it results in an S-shaped curve called sigmoid curve/growth curve.