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 therapeut ic plant, is today being evaluated for its antidepressant and antiretrovira l activities. The species is characterized by the presence of different typ es of secretory structure: translucent glands or cavities, black nodules an d secretory canals. The aim of this work was to characterize the translucen t glands and secretory canals in both the floral and vegetative parts, from morphological, anatomical and histochemical points of view. Translucent gl ands consist of a sub-epidermal cavity delimited by two layers of cells. Th ere are three types of secretory canal: type A, with a narrow lumen, and ty pes B and C, both with a wide lumen, but with different patterns of develop ment. Histochemical tests showed that all these structures contain alkaloid s 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.