Macro- and microscopical characterization of the stem and flowers of Malvaviscus arboreus Cav. (Malvaceae)

Malvaviscus arboreus Cav. (Sleeping Hibiscus) is a species of flowering plants belonging to family Malvaceae with a natural distribution throughout Central and South America. However, this perennial, medium-sized shrub has been also widely cultivated in several other tropical and subtropical areas of the globe. Sleeping Hibiscus is characterized by an erect, cylindrical, and glabrous stem with monopodial branching, reaching up to 0.5‒1 m in height and 0.2‒1 cm in diameter. The stem carries simple, alternate, oval or ovate to broadly cordate leaves and red solitary flowers. Flowers of Sleeping Hibiscus are tube-shaped with totally wrapped petals that only slightly open at the top, carried on hairy, pendulous green pedicels. Besides their ornamental value, M. arboreus plants enjoy multiple folk, medicinal, and culinary applications worldwide owing to their wide range of bioactive secondary metabolites, principally phenolics. Hence, in continuance of our interest in this medicinal plant, which included formerly the comprehensive botanical description of its leaves, along with the phytochemical and biological characterization of its leaf and stem extracts, this paper presents the macro- and microscopical characters of M. arboreus stems and flowers. Such botanical data collectively draw a helpful image regarding the identification and authentication of this plant species.