The allelopathic effects of crude water extracts of Annona muricata on common weeds

Annona muricata (sour sop) belongs to the family Annonaceae. This plant inhibits the growth of other plants growing around it, a phenomenon called “allelopathic effect”. Allelopathy is the production of specific biomolecules by plant species mostly secondary metabolites that can induce suffering or give benefit to other plant specie around it. Crude water extraction of the leaves stems and roots of Annona muricata were applied on common weeds in three different locations marked as areas A, B and C respectively and the morphological and physiological effects of the application on the common weeds observed and recorded. The outcome of this research work showed that extracts from all the parts of the plant inhibit the growth and development of other plant species such as phyllantus spps, Panicum maximum, Tridax procumbens etc. The absorption of the extracts through the roots of such plants affected their physiological processes such as photosynthetic, respiratory and transpiratory rates, stomatal closure as well as reduced chlorophyll content leading to wilting, maceration of tissues, stunted growth and finally death of the affected plants. International Journal of Natural and Applied Sciences Vol. 2 (4) 2006: pp. 341-34

Petiolar anatomy of eight Nigerian species of Vigna savi (Leguminosae-papilionoideae)

An investigation on the petiole anatomy of eight Vigna species namely V.ambacensis, V.gracillis, V. racemosa, V. reticulata, V. subterranea, V. triloba, V. unguiculata and V. vexillata were carried out. Anatomically significant features were found in the petioles of the taxa investigated. The presence of crystal sand crystals in the petioles of V. ambacensis, V. triloba and V. unguiculata distinguished these three taxa from V. gracillis with aggregate crystals and V. racemosa with rectangular and crystal sand crystals. The absence of any form of crystal in the petioles of V. reticulata and V. subterranae is also a taxonomic character that can be used to distinguish these two taxa from the rest of the taxa studied. Another interesting feature of the anatomical studies of the petioles is the similarities in tissue distribution in V. reticulata, V. unguiculata, V. racemosa and V. subterranea suggesting that these taxa have inter specific relationships. Keywords: Anatomy; Vigna; petiole; species; taxonomy International Journal of Natural and Applied Sciences Vol. 2 (3) 2006: pp. 193-19

Nodal anatomy of eight Nigeria species of Vigna savi (Leguminosae – Papilionoideae)

An investigation on the nodal anatomical features of eight Vigna species namely: V. ambacensis, V. gracills, V. racemosa, V. reticulata, V. subterranae, V. triloba, V. unguiculata and V. vexillata that are common in Eastern Nigeria were carried out. The model anatomy showed that these taxa possess useful taxonomic characters that can be used to establish inter specific relationships among the investigated taxa. V. ambacensis possessed crystal sand and vessels, V.gracillis has both aggregate and crystal sand crystal with numerous vessels. V. racemosa is characterized with aggregate, crystal sand crystals and vessels while V. reticulata has only aggregate crystals and vessels. V. subterranea has vessels with cells that are irregular in shape while V. triloba has aggregate crystals and vessels. In V. unguiculata, there are rectangular and crystals sand crystals and vessels while V. vexillata has rectangular crystals and vessels. Moreso, the epidermal walls of V. gracillis, V. reticulata, V. vexillata and V. triloba have multiseriate pentagonal cells. The presence of these nodal anatomical features is discussed in relation to their taxonomic significance. Keywords: Anatomy; node; Vigna species; taxonomy; NigeriaInternational Journal of Natural and Applied Sciences Vol. 2 (3) 2006: pp. 178-18

Palynological studies on five species of Asteraceae

Palynological studies on five species of the family Asteraceae namely Guternbergia nigritiana, Emilia praetemissa, Vernonia guineensis, Lagera pterodonta and Chromolena odorata was carried out. Resultsobtained from this investigation showed that the pollen shape is spheroidal in G. nigritiana, E. praetermissa and C. odorata while it is elliptic in V. guineensis and L. pterodonta. The pollen aperture isporate in all except in L. pterodonta where it is elliptic. The pollen wall is echinate in all except in C. odorata where it is smooth. The general appearance of the pollen grains is circular in G. nigritiana, E.praetermissa and C. odorata but longer than wide in V. guinensis and L. pterodonta. It is therefore likely that the nature of the pollen grains in these species could be an evolutionary modification ofteninherited to determine the mode of pollination and thereby perpetuate a particular group of plants. The similarities in structure showed interspecies relationships and reasons for them to be in the samefamily while the differences in structures showed reasons for them to exist as distinct species