Internal secretory structures in Hypericum patulum - a selection of optic microscopy images

Abstract

Hypericum patulum (goldencup Saint John’s wort, fam. Hypericaceae) is an exotic shrub, originated from China, widely cultivated in gardens in temperate regions as ornamental, for its large, golden yellow flowers and thick, green, deciduous or persistent foliage. Similar to Hypericum perforatum (common St. John’s wort), which is a well-known valuable herbal drug, some other Hypericum species also have some unusual internal secretory structures that produce and accumulate many bioactive compunds, thought to have evolved as a plant response to herbivore attack. In the present study the optic microscopy images of Hypericum patulum leaves, flowers and stem show: black nodules (spheroidal dark glands) which are glands that produce and accumulate a granular red to black colored pigment (hypericin) – they were seen in sepals and stem; pedunculate black nodules (glandular emergences) were seen on the margin of the sepals; secretory cavities (spheroidal pale glands or translucent glands) that are almost spherical or a bit elongated found in leaves and sepals, they have a cavity that is bordered by secretory cells that produce oils that diffuse through the cell wall and accumulates within the cavity, they are considered to produce hyperforin and essential oils; secretory canals with large lumen, that are long, tubular structures found in leaves mixed with translucent glands which have the same structure and origin.