Systematic significance of stipe anatomy of Pteris L. (Pteridaceae) from Southwestern Nigeria

Stipe anatomy of seven Pteris species collected from various locations in the Southwestern Nigeria was investigated. This was with a view to identify characters of the stipe anatomy that are important in delimiting the species. Transverse sections (TS) of stipe at proximal median and distal regions were cut with the aid of a Reichert Austria sledge microtome at 10 μ thickness. Sections were stained in Safranin O for five minutes, rinsed in three successive changes of water and counterstained in Alcian blue for five minutes. The counterstained sections were rinsed in three changes of water, and then treated in serial grades of alcohol. Observation of prepared slides was made under light microscope. Based on the shape of the vascular bundles, the Pteris species fall into three categories which are inverted Omega, V or U shapes. The adaxial grooves varied from proximal to distal regions in all the species except in P. ensiformis where it was uniform throughout the regions.