Auxanometer is an instrument used to measure the plant growth. Arc auxanometer is used by marking the difference in the position of the pointer before the experiment and after the deflection. This indicates the amount of growth of the stem and thus the growth of the plant. Pfeffer's automatic auxanometer is an improvement over the arc auxanometer. It can register total growth, rate of growth at specific time and overall pattern of growth. Vernier Callipers can be used for measuring diameter in case of cylindrical and globular organs. Measuring tape or a normal scale (ruler) is used to measure the length and diameter of large plant organs.