Comparative morpho-anatomical characteristics and phytochemical constituents of Aloe vera Barbadensis miller and Aloe vera var. Chinensis (haw) Berger
This study was set to investigate the comparative morphological and anatomical characteristics of Aloe vera barbadensis Miller and Aloe vera var. chinensis(Haw) Berger. These are evergreen perennials belonging to Asphodelaceae Juss. in the Order Asparagales Link. The former measures up to 80±20cm in height with lanceolate leaves and rosette habit. The leaves have spiny margins decorated with whitish spots on both foliar surfaces which disappear at maturity. The tubular flowers are orange and densely clustered at the stem apex; corolla is yellowish, tubular and up to 2.5±0.5cm in length whereas the latter is 40±10cm in height with rather lightly green rosette leaves and foliar white spots on foliar surfaces maintained at maturity. The two plants are fleshy and succulent with mild bitter taste. Leaves are amphistomatic with tetracytic sunken stomata. The cells of the epidermal layer are nucleated mostly hexagonal and include pentagonal, heptagonal to square or rounded. Stomatal indices for Aloe vera barbadensis adaxial foliar layer is 7.92 % and abaxial 4.76% while Aloe vera var. chinensis adaxial surface is 7.92% and abaxial 3.85%, not significant. Anatomical studies revealed the cell types from the epidermis, hypodermis, general cortex to the pith are similar in mid-ribs, petioles, stems and nodes. The roots have piths and vasculation is closed type. Phytochemical studies showed the presence of Alkaloids, flavonoids, saponins and tannins in both species, whereas combined anthraquinone was observed absent in both plants. Cardenolide, phlobatannins and free anthraquinones were present in Aloe vera var. chinesis but absent in Aloe vera barbadensis while cyanogenic glycoside was absent in Aloe vera var chinensis but present in Aloe vera barbadensis. The species are used in natural medicine. The information contained in this research would further aid in the taxonomic delimitations of these plants.