International Journal of Life Science and Agriculture Research

Taxonomic delimitation within the genus Eriosema (Fabaceae) in Nigeria has remained poorly resolved due to limited comprehensive revisionary studies and pronounced morphological overlap among species. This study presents the first quantitative taxonomic evaluation of Nigerian Eriosema species using numerical (phenetic) approaches to resolve species boundaries and identify diagnostic characters. A total of 55 specimens representing 11 species were collected from natural populations and herbaria, and 17 morphological characters (quantitative and qualitative) were selected following a priori screening. Each specimen was treated as an Operational Taxonomic Unit (OTU) and analyzed using multivariate techniques, including cluster analysis (UPGMA) and principal component analysis (PCA), implemented in PAST after log₁₀ transformation of the data. Cluster analysis separated the specimens into 11 distinct phenetic clusters at a similarity distance of 0.955, with a high cophenetic correlation coefficient (r = 0.84), indicating strong concordance between the similarity matrix and the phenogram. PCA results were congruent with clustering patterns, with the first two principal components explaining 77.3% of total variation. Key characters contributing most to species discrimination were leaflet tip, number of leaflets, leaf type, pod surface, and inflorescence type, while leaflet length, leaflet width, petiole length, and internode were more useful for species delimitation. The results confirm the taxonomic independence of the 11 species and demonstrate the effectiveness of numerical taxonomy in resolving morphological complexity. This study provides a robust framework for future taxonomic revisions of Eriosema in Nigeria and contributes significantly to systematic botany and legume biodiversity research.

Eriosema, Fabaceae, Morphometrics, Species delimitation.

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