A qualitative micromorphological assessment of the seven species of Isolona occurring in Nigeria and the Cameroons was undertaken with the aid of light microscope. The stomatal cells are particularly useful, providing stable characters which can be reliably employed in distinguishing the species. Hypostomatic leaves and paracytic stomatal type are generic constant. Possession of only paracytic stomata is characteristic of I. dewevrei whereas other species may have in addition another type such as 1+2 laterocytic stomatal type found only in I. zenkeri and presence of brachyparacytic stomata which shows relatedness of I. campanulata, I. congolana, I. hexaloba, I. pleurocarpus and I. thonneri. The epidermal surfaces appeared glabrous but an indication of hairs is shown by the presence of a glandular trichome base only in I. hexaloba. The epidermal cell characters such as epidermal cell shapes and anticlinal wall patterns seem to intergrade and they are not as definite as the stomatal cells. However, a combination of these features will be helpful in defining the species better and their leaf fragments can be differentiated based on the various characters studied for effective utilization in herbal medicinal research.

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A comparative study of the some leaf anatomical features of four species of Annona occurring in Nigerian was undertaken with the aid of light microscope. The four foliar structures (epidermis, petiole, midrib and lamina architecture) studied revealed useful characters which support recognition of the species. A combination of these features has been used to prepare an artificial indented dichotomous key for identifying the  species. The generic constant features encountered included hypostomata, paracytic stomatal type, linear nerves endings, uneven midrib outline, and centrally located vascular bundles in the petiole and midrib. However, the most reliable distinguishing characters found across the species included presence of brachyparacytic stomata in A. reticulata, presence of trichomes on the midrib in A. senegalensis, absence of druses on the abaxial surface in A. muricata and A. squamosa, a thick pitted anticlinal walls on the surfaces of A. muricata and consistent polygonal areola shape in A. squamosa. The overlapping characters which also justify the closeness of the species and their grouping in a genus were recorded in both the qualitative and quantitative features. Prominent among them are the mean stomatal width which is about 1.0 μm in all species, nerve endings within the areole which varies between 1-2, U- or V-shaped midrib on the adaxial surface and straight to curved anticlinal wall pattern. The significance of these observations is discussed in updating the existing data in the genus. Keywords: Epidermis, Microscopy, Midrib, Petiole,   Systematic

The comparative assessment of six (6) Isolona species occurring in Nigeria and the Cameroons was undertaking using GC-MS analysis. The analysis was carried out with methanol extract and one hundred and seventy-six ( 176) phytoconstituents identified and scored at different retention times ranges from 3.22min in I. hexaloba (Pierre) Engl. & Diels. to 34.56min in I. campanulata Engl. & Diels.. The prominent compounds were scored in carboxylic and its derivates while the least compound was identified in alkyne. Highest M.wt. was 741.5 in I. congolana (De Wild.&T.Durand) Engl. & Diels. at retention time of 34.52 min and the lowest M.wt. was 84.15 in I. thonneri (De Wild.&T.Durand) Engl. & Diels. at retention time 3.44 min. Hexadecanoic acid, methyl ester formula C17H34O2 and M.wt of 270.4was scored in all the six species suggested a diagnostic characters for the genus Isolona. Quantitatively, the amount of the analytes isolated in all the species ranges from 0.1% in I. hexaloba to 59.36% in I. thonneri. Two UPGMA distant trees were constructed with RMSD and Euclidean index to illustrate the relationships among the Isolona species based on the difference chemical constituents. The distance tree revealed the separation of I. thonneri from all other species, also a sub-cluster tree of I. hexaloba, I. campanulata and I. zenkeri (Engl.) Dyer. was also constructed. The highest distance value level is 9.576 scored between I. thonneri and I. congolana while the highest similarity level was 2.911 scored in I. hexaloba and I. campanulata. The overlapping phyto-constituents characters revealed the closeness of the taxa studied, this invariably will update the existing data in the genus and ultimately in the family Annonaceae.

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.