Distribution of insoluble polysaccharides in the shoot apex of Rhododendron arboreum Linn. during the annual growth cycle

Abstract

Starch grains occur all over the dormant shoot apex of Rhododendron arboreum except in the bud scales. They are abundant in the peripheral, rib and pith meristem cells. as well as in the youngest leaf primordia. Tannin is present in the entire dormant bud hut for the cells of the apical meristem and leaf primordia. Gradually, tannin degradation into numerous globules occurs. This is concomitant with the disappearance of starch grains and indicates the earliest structural manifestation of spring awakening by meristematic activity in the buds. The weak affinity of tannin globules to PAS is due to their hydrolysis which releases glucose for metabolic activities. Thus, a parallelism seems to exist between the metabolism of tannins and starch in relation to the various phases of bud development.