Benjamin C. Ndukwu

The value of morpho-anatomical features in the systematics of Cucurbita L. ( Cucurbitaceae ) species in Nigeria

Comparative studies on the morphology and anatomy of the three species of Cucurbita L. (C. moschata, C. maxima and C. pepo ) in Nigeria were carried out. The morphological features of significance include variations in the number of tendrils, fruit size, shape, nature of fruit stalk, leaf shape and flower colour. Seed-coat anatomy revealed four distinct zones, which varied in thickness and tissue layers. Similarities were observed in the distribution, differentiation and number of layers of cells and tissues in the leaf, petiole and stem sections. There were, however, variations in number of bicollateral vascular bundles in their petiole. While the number is 10 in C. moschata , 14 in C. pepo , it is 16 in C. maxima . Parietal placentation and 15 anther-lobes are reported for these species for the first time. The usefulness of these parameters in the taxonomic delimitation of these species is discussed. Key Words: Cucurbita , morpho-anatomy, placentation, seed-coat, taxonomy, vascular bundles. African Journal of Biotechnology Vo l.3(10) 2004: 541-546

Impact of four-dimensional seismic and production activities on the mangrove systems of the Niger Delta, Nigeria

Reconnaissance survey and laboratory appraisal of the mangrove system in seven communities in the Niger Delta (Nigeria) endangered by seismic and production operations revealed several alterations of soil, sediment, and vegetation. Hydrocarbon content in the range of 0.3–1.1 mg/100 g was extracted within the proximities of spill sources and seismic lines. The prospect area covered by our investigation was characterized by a mixed mangrove forest dominated by Rhizophora racemosa. It was observed that the construction of the seismic lines was responsible for the vegetal disorientation recurrent in the area. The grass, Paspalum vaginatum, and the saltwater fern, Acrostichum aureum, were found at the fringe of most dredge spoils. The characteristic tidal inundation which increases mobility of the substrate, salinity fluctuation, and anoxia may also have contributed, at least in part, to the observed despoliation of some of these species found within the vicinities of the seismic lines and hydrocarbon percolation. Extensive revegetation program is recommended to ensure an effective restoration process of this ecologically fragile zone.