Anatomical variations in stomatal attributes of selected species of family Asteraceae

Abstract

In order to document stomatal characters which are significant in taxonomy, a detailed microscopic study on leaf epidermis of the selected taxa from Asteraceae was carried out. The plant species were Sonchus oleraceus, Bidens bipinnata, Centaurea iberica, Conyza bonariensis, Helianthus annuus, Lectuca serriola, Parthenium hysterophorus, Tagetes erecta, Cosmos sulphureus, Launaea procumbens, Zinnia elegan, Galinsoga parviflora and Conyza canadensis. All the species were amphistomatic and four types of stomata i.e., tetracytic, anomocytic, anisocytic and tricytic were recognized. Tetracytic stomatal type was dominant followed by anomocytic. Stomatal density was high on abaxial epidermis than adaxial epidermis except in Conyza bonariensis and Conyza canadensis. Highest stomatal density was in Tagetes erecta while lowest in Conyza canadensis. In lower epidermis stomatal index was higher in Sonchus oleraceus followed by Bidens bipinnata and Tagetes erecta while in upper epidermis highest index was shown by Cosmos sulphureus. Stomatal aperture and guard cell size and density were also significant features in these species.