Hypericum elodes L. (Clusiaceae): The secretory structures of the flower

The type, structure, distribution, and ontogenesis of secretory structures of Hypericum elodes flowers were studied by light and scanning electron microscopy. This species, widespread in Western Europe but present in Italy in one site only (S. Rossore Estate, Pisa), is characterized by the presence of glandular emergences, stipitate glandular pockets, and secretory canals. Each glandular emergence consists of a multicellular peduncle and a multicellular secretory head. The head is a compact structure that looks like the well-known black nodules of H. petybratum. The stipitate glandular pockets consist of a short multicellular peduncle and a multicellular head with a cavity that collects an amber-colored secretion. Two types of secretory canals were identified: a type with a narrow lumen, and a type with a wide lumen. Histochemical analysis showed that secretion is similar in all secretory structures, and is rich in lipids, essential oils, alkaloids, and oleoresins.