ABSTRACT
Bioactive substances are found in all plant organs. They appear in the bark (Cinchona), in flowers (Chamomilld), in fruits (Papaver), and in leaves (Digitalis). Nevertheless the root/rhizome system seems to be a preferred depository of bioactive compounds. The relatively high concentration of bioactive metabolites in plant roots is probably related to their role as defense compounds. Toxic and physiologically active metabolites that protect roots from pests such as insects and other animals and from causes of diseases, such as bacteria, fungi, and viruses.
