Seed and trichome morphology of the Egyptian Fagonia (Zygophyllaceae) with emphasis on their systematic implications

Seed and trichome morphology of 13 taxa representing the genus Fagonia in Egypt have been studied using light (LM) and scanning electron microscopy (SEM). Macro- and micro-morphological characters, including seed shape, seed size, seed coat sculpture, trichome density and structure were studied to evaluate their systematic significance. Seed shape and trichome density were found to have only minor taxonomic value, but seed coat sculpturing and trichome structure proved to be valuable characters. These characters offer evidence to combine certain species, e.g. Fagonia kassasii and F. schimperi in F. bruguieri, Fagonia microphylla in F. scabra and Fagonia thebaica in F. arabica. However, F. sinaica, F. tristis, F. boveana and F. isotricha should be maintained as separate species. Generally, the different patterns of seed and trichome morphology are useful in delimitation of species within the genus Fagonia, but they could not be used to characterize groups of related species.