Translucent glands and secretory canals in Hypericum perforatum L. (Hypericaceae):: Morphological, anatomical and histochemical studies during the course of ontogenesis

Hypericum perforatum L., traditionally used in folk medicine as a therapeutic plant, is today being evaluated for its antidepressant and antiretroviral activities. The species is characterized by the presence of different types of secretory structure: translucent glands or cavities, black nodules and secretory canals. The aim of this work was to characterize the translucent glands and secretory canals in both the floral and vegetative parts, from morphological, anatomical and histochemical points of view. Translucent glands consist of a sub-epidermal cavity delimited by two layers of cells. There are three types of secretory canal: type A, with a narrow lumen, and types B and C, both with a wide lumen, but with different patterns of development. Histochemical tests showed that all these structures contain alkaloids and lipids but not pectic-like substances and proteins. Tests for resins, essential oils and tannins gave different responses in different parts of the plant. (C) 2001 Annals of Botany Company.