Characterization of the two species of Melochia L. in Nigeria

Abstract

Melochia corchorifolia L. and Melochia melissifolia Benth. have food and medicinal values; however, they are being misidentified. It is  therefore necessary to characterize these species comprehensively to establish their taxonomic status. This study employed botanical  and cytological parameters to characterize the two Nigerian Melochia species following standard methods and it was carried out at the  Department of Botany, Obafemi Awolowo University, Ile-Ife, Nigeria between 2020 and 2022. The result showed that M. corchorifolia could  be distinguished from M. melissifolia by its erect and annual habit, numerous, predominantly terminal inflorescences and white  petals without pigmentation. Melochia melissifolia was procumbent, perennial with a few principally axillary inflorescences, pink flowers  with pigmentation on petioles, stem and tip of the fruits. The leaf adaxial stomata type, foliar trichome type, midrib and vascular bundle  shapes, presence or absence of starch grain, tylose, brachysclereids, axial parenchyma, and phloem fibre could be used to delimit the two  species. They possessed monad, oblate to prolate spheroidal pollen grains with high pollen stainability. In addition, triad pollen was  observed in M. corchorifolia. Chromosome numbers of 2n=4x=28 and 2n=8x+2=58 were recorded in M. corchorifolia and M. melissifolia  respectively. Both species had high pollen stainability. The germination percentage was high and low in M. corchorifolia and M. melissifolia  respectively. The study revealed many similarities between the two Melochia species, indicating their close genetic  relationship as well as having a common origin. Nevertheless, the two species could be separated from each other with certain  morphological and anatomical characters, chromosome counts and some reproductive parameters. Therefore, the two Nigerian Melochia  species studied are distinct species from a common ancestor.