Foliar and pollen variation among Parkia R. Br. species in Nigeria

The genus Parkia is an evergreen flowering plant group of the family Fabaceae. In the present study, four species of the genus- Parkia biglobosa, P. bicolor, P. clappertoniana and P. filicoidea were investigated using Light Microscope (LM) and Scanning Electron Microscope (SEM) to elucidate the inherent characters that may be useful for their taxonomic study. Thus, we provided additional characters for the delimitation of the species in Nigeria, using leaf and pollen materials from fresh samples and previously deposited herbarium specimens. The characters include shape of epidermal cells, distribution of stomata trichome character, pollen type, pollen size and exine sculpturing. Based on foliar anatomical characteristics, epidermal cells were polygonal in P. biglobosa, irregular in P. bicolor and P. filicoidea¸ while they were irregular to polygonal in P. clappertoniana. Non-glandular uniseriate trichome type was observed in all species studied. The pollen grains of the species studied were polyads. Exine pattern show variations such as minutely reticulate in P. filicoidea, reticulate in P. clappertoniana, coarsely reticulate in P. bicolor, and finely reticulate in P. biglobosa. The smallest pollen was observed in P. bicolor (82.5 x 84) µm2 and the largest in P. filicoidea   (96.2 x 105.6) µm2. The study revealed descriptive micro-morphological structures which could serve as supplementary information and references for the taxonomic description, identification and delineation of the species studied.