Epidermal Structures and Stomatal Ontogeny in Terminalia catappa L. (Combretaceae)

Stomatal ontogeny and epidermal characteristics of Terminalia catappa L., an important tropical economic plant, were studied and described. The central portions of cotyledonary and mature leaves were peeled, stained with acetocarmin, 1% safranin and fast green stains as required, mounted on microscope slides and observed under Olympus photomicroscope for stomata ontogeny and developmental stages. The cells of the epidermis of the species are polygonal, isodiametric or elongated in various directions and arranged irregularly. The anticlinal epidermal walls are sinuous, undulating, straight or arched. Combretaceous eglandular trichomes were observed on the abaxial surface of the cotelydonary leaves. Six types of stomata (anomocytic, tetracytic, stuarocytic, anisocytic, isotricytic, diacytic) and different transitional stages were also observed. Stomata occurrence in cotyledonary leaves was observed to be amphistomatic but hypostomatic in mature leaves. The adaxial stomatal index on the cotyledonary leaves ranged from 3.57-14.29 (9.61±3.15) while on the abaxial surface it varied from 12.50-31.25 (23.50±5.13). The ontogeny of isotricytic stomata is mesogenous; it is however mesoperigenous in anomocytic, tetracytic and anisocytic stomata types. Stomata clusters are frequent on the abaxial surface of mature leaves while contiguous stomata and abnormal stomata with unequal guard cells are rare. Stomatal ontogeny, an important taxonomic character, is described for the species.