Taxonomic Significance of Foliar and Stem Anatomy in the Delimitation of Piptadeniastrum africanum (Hook.F.) Brenan and Cathormion altissimum (Hook.F.) Hutch. & Dandy
Felix Okponanabofa Youkparigha
Department of Biological Sciences, Faculty of Science, Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria.
Bio Louis Nyananyo
Department of Plant Science and Biotechnology, Faculty of Science, University of Port Harcourt, Port Harcourt, Rivers State, Nigeria.
Glory Richard *
Department of Community Medicine, Faculty of Clinical Sciences, Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
The current monotypic status of the genus Piptadeniastrum Brenan is reasonably challenged as Cathormion altissimum is claimed to be closely related to Piptadeniastrum africanum – the only species in the genus – by some indigenous people of Bayelsa State. This work systematically examines this claim by studying some aspects of the foliar and stem anatomy of P. africanum and C. altissimum. Leaf peels and stem sections were made and analyzed according to standard procedures. Anatomical characteristics considered include stomata distribution, stomatal Index, type of stomata, the shape of leaf epidermal cells and anticlinal walls, the outline of the stem, and the arrangement of vascular bundles. Results showed that stomatal distribution in both plants was hypostomatic. Stomatal index and stomata type was 21.5% and mainly anomocytic, respectively, for P. africanum and 14.4% and primarily paracytic, respectively, for C. altissimum. Epidermal cell shape is irregular with undulating anticlinal walls in P. africanum, while epidermal cell shape is rectangular to polygonal with curved or straight anticlinal walls in C. altissimum. The outline of the stem is angular with four pronounced ridges and furrows in P. africanum, while the stem outline is wavy with very mild protrusions in C. altissimum. The differences in anatomical characteristics may justify the placement of these plants in different genera. Piptadeniastrum Brenan is monotypic.
Keywords: Piptadeniastrum africanum, Cathormion altissimum, anatomical character, anticlinal walls, paracytic, hypostomatic, stomatal index