Ultrastructure of the pollen grains in the family Bignoniaceae Juss. in Nigeria

Pollen morphology of eight species belonging to the Bignoniaceae in Nigeria was described using Scanning Electron Microscope (SEM). The species studied were Crescentia cujete Linn., Jacaranda mimosifolia D.Don., Kigelia africana (Lam) Benth., Markhamia tomentosa (Benth) K. Schum., Newbouldia laevis (P. Beauv.) Seemann ex Bureau., Spathodea campanulata P. Beauv., Stereospermum acuminatissimum Cham. and Tecoma stans. Reticulate exine ornamentation were observed in all pollen grains of the species studied. The shapes of most of the pollen grains were circular except from those of J. mimosifolia and T.stans which were elliptic. The pollen grains of all species examined were tricolpate (except from those of C. cujete which were non-aperturate) isopolar with long colpi and a reticulate tectum. The pollen grains of the species studied were radially symmetrical, isopolar or apolar. The general shapes were subspheroidal to prolate. The AMB is rounded to triangular. The apertures are usually three in number, always equatorially placed. This study points to a reclassification of the Bignoniaceae.