Leaf epidermal characteristics of Annonaceae Juss. and its taxonomic evidence in Nigeria and the Cameroons

Abstract

This study describes the comprehensive micromorphology and taxonomic evidence of 28 species of Annonaceae from Nigeria and the Cameroons using light microscopy to provide additional anatomical and morphological diagnostic characters to complement the systematics boundaries of the infrafamilial and tribal clades. The epidermal cell shape varies from polygonal to irregular on both or either surface except Annona reticulata with isodiametric on the adaxial surface. The anticlinal wall patterns are either undulated, straight, or curved in the family. The constant generic feature encountered includes hypostomata which are mostly paracytic except in Cananga odorata, Isolona zenkeri, Uvaria angolensis and Letestudoxa bella possessing pericytic, 1 + 2 laterocytic and stephanocytic, respectively. Hemiparacytics, brachyamphiparacytic and brachyparacytic stomata, which are variables of paracytic are also present. These stomata complexes proved useful in species delimitation and diagnostic of the family Annonaceae. Other foliar epidermal features were crystals of different shapes and sizes mainly of druses and styloid, unicellular trichome type, and anticlinal wall pattern. The pattern of affinity among the species suggested evidence of similarity and differences in the micromorphological characters, which cumulated to the distinct identification of each species. Based on the most reliable characters within the family, the k-means cluster, distance matrix, correlation coefficient, and UPGMA dendrogram tree were constructed.