The annual rhythm of activity of the lateral meristems (Cambium and Phellogen) in Cupressus sempervirens L

The annual rhythm of cambial activity in Cupressus sempervirens seems to be endogenous and fits well the Mediterranean climatic rhythm. Under outdoor conditions the cambium begins its activity towards the autumn when temperatures drop and water is less limiting. The cambium continues to be active during the mild Mediterranean winter and enters dormancy towards the beginning of the dry summer. A constant supply of water is not enough to avoid cambial dormancy but may result in earlier onset and a prolonged period of activity. Relationships between xylem and phloem production, between shoot and root, and between cambial and phellogen activity are discussed.