The value of leaf micromorphological in the taxonomic delimitation of Emilia cass. (Asteraceae) species

Studies were carried out on the leaf epidermis of the three species of Emilia: E. coccinea (Sims) G. Don, E. praetermissa Milne-Redhead, and E. sonchifolia (L) DC using light microscope. Epidermal cells in the species are irregular with anticlinal wall pattern sinuous in E. coccinea, sinuous in E. sonchifolia, and straight to arcuate in E. praetermissa. Epidermal cell dimensions were highest in E. praetermissa with 52.50µm and 49.64µm for the length and breadth respectively. The epidermis is hypostomatic with anomocytic stomata in all species, semi-contiguous to contiguous stomata in E. coccinea, and E. sonchifolia. Stomata index (S.I), frequency and size differed in all species. While S.I of 34.80 in E. sonchifolia was the highest in the genus, E. coccinea had the lowest S.I of 21.90. Stomata ledges occur in E. coccinea and E. praetermissa. Simple unicellular trichomes were observed only on the abaxial surface of E. coccinea. The usefulness of these data to the taxonomic delimitation of the Emilia is discussed. Keywords: Emilia, epidermis, stomata, taxonomy, trichomeGlobal Journal of Pure and Applied Sciences Vol. 12(2) 2006: 183-18