Investigation of secretory structures in some of the Hypericum species in Iran

The genus Hypericum L. (Hypericaceae), consisting of about 500 species shows a worldwide distribution from which 19 grow in Iran. A wide range of biologically active compounds particularly with anti-depressants e.g., naphthodianthrones (e.g. hypericin and pseudohypericin) have been identified in this plant. The aim of this study was to evaluate the relationship between the anatomical, histological and morphological features in this genus. for this purpose the anatomical structure and histological traits of vegetative and generative organs of the species: H. dogonbadanicum, H. androsaemum, H. perforatum, H. tetrapterum, H. scabrum, H. triquetrifolium, H. asperulum, H. lysimachioides, H. elongatum, H. hirtellum, H. davisii, H. apricum, H. helianthemoides, H. vermiculare, H. hirsutum, H. linarioides, H. armenum were examined. This study showed that secretory tissues including secretory canals, translucent glands and black glands yielded the most useful features for our purpose. These structures are generally located in stems, leaves, petals and sepals, flags and carpel; although depending on the species and organs they may show some differences. Secretory ducts showed a general presence in all the species studied however number and position of them were different. Furthermore, secretory cavities were revealed in all the species examined; but differed based on their pore diameter and location. The dark nodules were seen in some species and organs. Based on the above observations, a diagnostic key was constructed and provided here which showed a fully accordance with the already prepared morphological ones.