Structure and functions of the vascular cambium

Following a general outline on the functioning of the cambium, the authors review the data acquired over the last 20 years. The interest is focused on : i) the ultrastructural characteristics of the two kinds of initials; ii) the early structural, metabolic and molecular modifications occurring durin g the first stages of daughter cell differentiation into either xylem or ph loem; iii) the complex rhythmic changes of structure, metabolism and activi ty undergone by cambial cells during the seasonal cycle; iv) the characteri stics and control of the cessation of cambial activity in autumn and of its reactivation in spring; v) the main research approaches in cell and molecu lar biology presently open to the students of the cambial meristern. (C) Ac ademie des Sciences/Elsevier, Paris.