This book summarizes the wide field of biomonitoring of heavy metals in terrestrial by the use of plants. It was not attempted to provide a uniform terminology of bioindication (biomonitoring), and therefore it varies from chapter to chapter due to the many different views that coexist at present. The book rather gives a survey of the state of the art of this expanding field based on the authors' work. Both, contradictory and complementary aspects of bioindication (biomonitoring) are pointed out to the attentive reader.