Trichomes Morphological Diversity in Some Species from Related Tribes of Asteraceae Family in Iraq

Abstract

      This study includedepidermal appendages characters of ten species belongingto the familyAsteraceae.Most of the studied species are characterized by eglandular, glandular, trichomesand papillae which are variable according to itskind, number of cells, shape, dimensions, characteristicsof surrounding cells, wall thickness and the position. Results showed that all species included glandular and eglandulartrichomes exceptCosmos bipinnatus, Ecliptaprostrate, andEupatoriumcannabinum that lacked in glandular trichomes and were based on their specific details.Trichomes were divided into different groups. The glandular ones involved sessile glandular or group multicellular and the head wasmace-shaped or rounded.Whereaseglandulartrichomes are classified into various groups,unicellular trichomes group with obtuse or acute apex or with tuft shape or dendroid, dicellular.Trichome group uniserriate or biserriate, and multicellular trichome group which is widely different in their shapes, dimensions, number of cell and the position. Papillae distributed on stem, corolla, and stigma have triangular-shape with acute apex or finger-like shape with obtuse apex.Hence,trichomes reveal a taxonomic importance in species identification and determine the relationships among them in their tribes.