Achene and pollen morphology of the genus Crepis L. in Egypt and its systematic significance

In this study, achene, and pollen morphology of Crepis L. species in Egypt were investigated by scanning electron microscopy.Crepis genus is represented by eight species viz C. aculeata (DC.)Boiss., C. aspera L., C.libyca (Pamp.)Babc.C. micrantha Czerep., C. nigricans Viv., C. sancta (L.) Bormm., C. senecioide Del. and C clausonis pomel.However, due to occurrence uncertainty regarding C. clausonis in Egypt, this study focuses on the remaining seven species.The achenes exhibit morphological diversity, being either homomorphic or dimorphic, with or without a beak, and occasionally winged.Their surface texture varies from smooth to spiculate or scabridulous, with longitudinal ribbing.The pappus is either persistent or deciduous and consists exclusively of setae.Key diagnostic features for differentiating Egyptian Crepis species include achene polymorphism, variations in surface sculpturing, shape, beak presence, width, and the minimum and maximum lengths of both peripheral and central achenes, as well as pappus length.The pollen grains of Crepis species are characterized as echinolophate and 3-colporate, with apertures located in poral lacunae forming compound structures.The polar area is distinctly defined and covered with echinae.Morphological features such as pollen grain shape and polar area structure hold significant taxonomic value for species delimitation within the genus.This study highlights the importance of achene and pollen traits in distinguishing Crepis species in Egypt and provides valuable insights for their taxonomy and classification.