Paradermal Studies on the Stomata of some Species of Asteraceae

Stomata are specialized structures responsible for exchange of gases i.e. CO₂ and O₂ between plants and the environment thereby performs two important physiological functions, viz., photosynthesis and respiration. The structure of stomata is considered as important taxonomic tool for identification of plants. The present paper deals with the paradermal studies on the stomata of 15 species of family Asteracece done through light microscope and scanning electron microscope. The study reveals a considerable difference in the structures and number of stomata found on the adaxial and abaxial surfaces of the leaf. Two types of stomatal types viz. anomocytic (irregular celled) and anisocytic (unequal celled) were observed in the present study. Stomatal density was found to be ranging from 41.519 mm^-2 (Gillardia pulchella) to 276.166 mm^-2 (Helianthus annuus) on the abaxial surface of leaves while 23.90 mm^-2 (Gillardia pulchella) to 225.83 mm^-2 (Wedelia trilobata) on the adaxial surface of leaves of selected species of Asteraceae. Stomata of 13 species were of medium size and only two species Gillardia pulchella and Zinnia multiflora showed stomata to be of large size.