Importance of Leaf, Stem and Flower Stalk Anatomical Characters in the Identification of Emilia Cass

Three species of Emilia Cass. namely E. cocinea (Sims.) G. Don, E. sonchifolia (Linn.) DC and E. preatamissa Milne-Redhead were investigated using their petiole, stem, flower stalk, midrib and epidermal features. The specimens were pretreated, sectioned, stained in 1% Safranin O for two minutes, counter-stained with Alcian blue, mounted on a slide, observed under microscope and micro-photographed using Leica WILD MPS 52 microscope camera on Leitz Diaplan microscope. The results revealed that the variation in number of vascular bundle in the petiole, stem, flower stalk and midrib, stomata type, occurrence (on the adaxial and abaxial leaf surfaces) and orientation (contiguous or in groups) constituted dependable diagnostic characters among the species studied. In this study for instance, the contiguous stomata is restricted E. cocinea. The dipolar contiguous stomata are found on the adaxial leaf surface while mono-polar, lateral and di-polar contiguous stomata were found on the abaxial leaf surface. Also, stomata in groups of 2, 3 or more were found on the leaf surfaces of the Emilia species. Among the species, E. sonchfolia and E. cocinea have stomata in groups of 2, 3 or more on both the adaxial and abaxial leaf surfaces while E. preatamissa was distinct form these species by having stomata only in groups of 2 on the upper surface of the leaf. This also revealed that there are intraspecific and interspecific relationships among species.