Question

Stomatal index 'I' is equal to
(where S $=$ number of stomata per unit area and $E=$ number of epidermal cells in the same unit area)

• A. $\frac{S}{E-S}$
• B. $\frac{S}{E+S}$
• C. $\frac{E}{S+S}$
• D. $\frac{E+S}{E}$

Answer 1

The correct option is B $\frac{S}{E+S}$

Stomatal frequency is number of stomata per unit area of leaf. Stomatal frequency varies according to cell size and smaller guard cells are usually associated with higher stomatal frequency, stomatal index relates the number of stomata per unit leaf area to the number of epidermal cells plus guard cells per unit leaf area. Thus, stomatal index is the number of stomata per unit leaf area relative to the number of guard cells. The mathematical relation for stomatal index is
[(No. of stomata per unit leaf area)] / [(number of stomata per unit leaf area) + (number of epithelium cells per unit leaf area)]