Although two important publications have already been issued on the plant ecology of arid and semi-arid regions, it has become apparent that a study dealing specifically with medicinal plants of those regions could be expected to be of considerable interest both to botanists and to pharmacologists; apart from its scientific value, it can provide invaluable indications of the directions in which research on medicinal plants is leading and of the practical possibilities of using such plants in the present-day economy.

UNESCO's arid zone programme, drawn up in 1951, was raised to the status of a major project at the ninth session of the General Conference in 1956. While the change has brought a substantial increase in the resources granted to the Organization for the promotion of arid zone research, specifically by direct support for certain institutions in the region extending from North Africa to the Middle East and South- East Asia, the collection and dissemination of scientific information provided by studies on arid zone problems remain essential objectives.