The dorsiventral, amphistomatic, hairy leaf of Pelargonium odoratissimum was lacking the variety of the anatomical features considered advantages for the Mediterranean plant life compared to the leaf of most Mediterranean xerophytes. Conversely, it had a well-equipped and intensely functioning secretory apparatus. Light, scanning, and transmission electron microscopy were employed to investigate the leaf structure while histochemical reactions traced the nature of the secreted metabolites. The numerous trichomes of the leaf were very active in producing phenolics, terpenes, and flavonoids mixed in a fragrant essential oil accumulated in an ovoid chamber at the top of each secreting hair. In-vitro cell cultures may be used for the production of novel compounds from low-cost precursors. © 2013 Taylor & Francis Group, LLC.

The anatomy of the dorsiventral, amphistomatic leaf of Papaver rhoeas was investigated. It was a simple structure possessing large epidermal cells having their vacuole impregnated with glycoproteins which varied in texture, forming a dense, hard core in the middle of the vacuole. Slender rays of cisternae radiated from the dense central core to the cell wall. Thin-walled palisade cells presented a unique, lobed shape probably creating larger surfaces for gas exchange. Mesophyll cells secreted phenolics, condensed tannins, alkaloids, terpene containing steroids and sesquiterpenes. P. rhoeas although being a therophyte, has adopted some structural features common in mediterranean phanerophytes. © 2013 Taylor & Francis Group, LLC.