Morphological studies on trichomes of Brassicaceae in Egypt and taxonomic significance

Trichomes morphology, structure, and taxonomic significance of 82 species belonging to 9 tribes of Brassicaceae from Egypt were studied using light microscopy (LM) and scanning electron microscopy (SEM).This work was largely based on herbarium material in addition, fresh material of most of the taxa was studied.A total of twelve trichome types could be distinguished and classified into unicellular or multicellular based on the structure of the hair.The unicellular trichomes could be distinguished as simple, hooked, vasculate, clavate simple glandular, appressed medifixed, trifixed, Y-shaped, branched (3-4 fids), dendroid and stellate.The multicellualr trichomes were glandular.We found trichomes as being valuable characteristics for identification of tribes, genera, species, subspecies, and varieties in Brassicaceae.A key for the identification of the investigated taxa based on trichome characters is provided in this paper.