The annual rhythm of cambial activity in four subshrubs common in phryganic formations of greece

The annual rhythm of cambial activity and the pattern of starch accumulation in pith and ray cells of four seasonal dimorphic subshrubs typical of Greek ‘“phrygana,” Sarcopoterium spinosum, Thymus capitatus, Phlomis fruticosa and Cist us incanus were investigated. Cambial activity in all species examined was found to occur during the winter when temperatures are low. During the rest of the year, cambium remains dormant. At the time of high cambial activity, starch content of pith and ray cells diminishes. High accumulation of starch grains was found to occur after cambial activity ceases in S. spinosum and a moderate starch accumulation occurs in C. incanus whereas there is no starch content in the pith of T. capitatus and P. fruticosa throughout the year. These results indicate that concerning their cambial activity, phryganic species behave like typical desert plants.