Morphological and anatomical characteristics of endemic Rosa arabica ( Rosoideae, Rosaceae) from Sinai, Egypt.

Rosa arabica is endemic to the high mountain area of the St. Catherine Protectorate, Southern Sinai, Egypt. It has been listed as Critically Endangered in the IUCN Red Plant List. The present study aimed to provide detailed morphological and anatomical characters of the endemic Rosa arabica by using light and scanning electron microscopy in order to expand knowledge of its taxonomy. The present study revealed the presence of three types of trichomes: simple unicellular, glandular unicellular stalked and glandular multicellular multiseriate. Anomocytic stomata, occasionally hemiparacytic and actinocytic were observed mostly on abaxial surface. Epidermal cells were smooth, with dispersed wax granules and stomata slightly raised with outer stomatal rim. Druses were also reported in pith and cortex of stem and petiole. Achene micromorphology showed scalariform pattern with anastomosed raised anticlinal walls and depressed periclinal walls. These data are presented here for the first time and their taxonomic values are discussed.