Ultra-Structure of the Leaf Surfaces of the Family Bignoniaceae Juss. in Nigeria

Abstract

The leaf surfaces of the Nigerian Bignoniaceae were studied using the Scanning Electron Microscope (SEM). The species in this study were: Crescentia cujete Linn. Jacaranda mimosifolia D. Don., Kigelia africana (Lam) Benth. Markhamia tomentosa (Benth) K. Schum., Newbuldia laevis (P. Beauv.) Seemann ex Bureau. Spathodea campanulata P. Beauv. Stereospermum acuminatissimum K. Schum. Stereospermum kunthianum Cham. Tabebuia rosea (Berthol) D. C. Tecoma stans (Linn) H, B &K. and Tecoma capensis. The study was conducted using anatomical characters to identify and delimit the Nigerian taxa at the tribal level. Stomata were observed on the abaxial surfaces of all the species studied. Sunken stomata were found in K. africana while the others had raised stomata. Peltate trichomes were found on some species like the abaxial surfaces of C. cujete, J. mimosifolia, M. tomentosa, N. laevis T. stans and T. rosea and on the adaxial surfaces of C. cujete, M. tomentosa, N. laevis, S.acuminatissimum and T. rosea. M. tomentosa had both glandular and non-glandular trichomes on the abaxial surface while T. capensis had only non-glandular trichome on the adaxial surface. The non-glandular trichomes of M. tomentosa were long and with blunt tip while those of T. capensis were short and with pointed tips. Striae were found on the abaxial surfaces of J. mimosifolia and T. stans and on both the abaxial and adaxial surfaces of T. capensis. The genera Tabebuia and Tecoma are suggested to be retained in the tribe Tecomeae based on striations on their epidermal cells. While other members be assigned to a new tribe ‘Spathodeae’.