CYTOTAXONOMIC STUDIES ON NIGERIAN VERNONIA ADOENSIS LOWE & SOLADOYE

Abstract

Nigeria, the study area lies between latitude 40 and 140 north of the equator and between longitudes 30 and 150 east of the Greenwich meridian with two major landforms- lowlands and highlands. The vegetation is made up of forests in the southern part and savanna in the northern part. The major soil types are ferruginous tropical soils, lithosols, vertisols, regosols, ferrasols and alluvial soils. Cytological and morphological studies were carried out on Nigerian Vernonia adoensis Lowe & Soladoye. Chromosome counts of n=10 was obtained for Vernonia stenostegia while V. tenoreana and V. kotschyana had n=9 which differed from earlier report. Pollen fertility test revealed that the 3 different species had normal regular bivalent pairing during meiosis, suggesting that they were diploids and hybridization was not responsible for their differences. Anonocytic stomata withagenous ontogeny was observed in all the 3 species, the epidermal walls of the 3 species differed from each other, the presence of contiguous stomata in V. tenoreana and the presence of eglandular multicellular trichomes in V. stenostegia and V. tenoreana is reported for the first time. the achenes of the 3 species differed from each other. Ecological, morphological and cytological observations have been discussed. They have proved that the habit and habitat preference is not responsible for their differences and thus V. adoensis was actually 3 species lumped together.