Comparative Anatomy and Numerical Studies of the Genus Stipagrostis Nees (Poaceae) in Egypt and their Taxonomic Significance

A comparative anatomy of the genus Stipagrostis Nees growing in Egypt was conducted using light microscopy and numerical analysis to evaluate their diagnostic value for systematic studies. Descriptions of stem and leaf cross-section: shape, outer frame boundaries, sclerenchyma and vascular bundles, assimilatory tissue, bundle sheath, and bulliform cells are presented. The results of the present study show beneficial data for evaluating the taxonomy of the genus Stipagrostis in Egypt at infrageneric, specific, and infraspecific levels. Five shapes were recognized for the stem outline section and three for the leaf blade. Moreover, three types of Stipagrostis leaf vascular bundles were identified: primary, secondary, and tertiary, varying in their shapes from elliptical to round. Leaf bulliform cells were located on the adaxial surfaces. They may be regular, irregular, and fan-shaped. Our result reveals that the genus Stipagrostis is represented by 14 taxa (12 species and two varieties) in Egypt. A diagnostic key for identifying studied taxa based on anatomical investigated leaf and stem characters was presented.