Hand-Harvested Organic Olive Leaves. Olive tree leaves are rich in a particular substance, oleuropein, a bitter glucoside. Oleuropein can be found in large quantities in olive tree leaves. Hydrolisis of oleuropein generates molecules which are very important for our health: Elenolic Acid, Hydroxytyrosol, Tyrosol and Rutin. a unique plant adding to human wellbeing. Also known as Hyssop and other names.