ABSTRACT
Studies on the influence of climatic and geographical factors on the constituents produced by medicinal plants are rarely consistent with regard to plant material or the experimental conditions. In order to study relationships between medicinal plants and general environmental factors, two distribution maps have been established, the first for the tropical and subtropical zones and the second for the temperate zones. The distribution of medicinal plants is considered in relation to their occurrence in main potential vegetation zones. This vegetational zone possesses a climate characterized by an 8 to 10 month long dry period. The climate of this zone is termed "Mediterranean" with a warm, dry summer and a mild, wet winter. The cold winter and the late drought summer limit the growing season of the steppe plants. The forest type corresponds to a warm temperate climate without well-marked dry periods and without winter frost.
