Calculation of Stomatal Number, Stomatal Index, Vein-Islet Number, Vein Termination Number, and Palisade Ratio

Stomatal Number, Stomatal Index, Vein-Islet Number, Vein Termination Number, and Palisade Ratio are all used to calculate leaf constants.

What is Stomatal Number?

It is the average number of stomata per square mm of leaf epidermis.

What is Stomatal Index?

This is the percentage ratio of the number of stomata to the total number of epidermal cells, with each stoma considered as a single cell.

Calculation of Stomatal Index

The following formula can be used to calculate the stomatal index:

Timmerman (1927) and Rowson (1943) were among the first to study the effects of stomatal number and index.

What is Vein-Islet Number?

The number of vein islets per square mm of the leaf surface midway between the midrib and the edge is known as the vein-islet number.

It is a constant for a given plant species and is utilized as a distinguishing feature for allied species identification.

Levin calculated the number of vein-islets in different dicot leaves in 1929.

What is Veinlet Termination Number?

The number of veinlet terminations per sq. mm of the leaf surface midway between the midrib and the edge is known as the veinlet termination number. The ultimate free termination of a veinlet is a vein termination.

In 1951, Hall and Melville determined the veinlet terminal number for separating Indian and Alexandrian Senna.

Read: Closing & Opening, Structure, Types and Functions of Stomata

What is Palisade Ratio?

The average number of palisade cells beneath each epidermal cell is known as the palisade ratio.

Palisade ratio can be calculated with the powdered medication, unlike vein-islet number, which requires an unbroken section of the leaf to be determined. In their investigations on Compositae.

Zorning and Weiss (1925) devised the palisade ratio determination approach.

For example, the number of vein-islets in Alexandrian senna is 25–29.5, but the number in Indian senna is 19.5–22.5. Alexandrian senna has a stomatal value of 10–15, but Indian Senna has a stomatal index of 14–20.