On the Ultrastructure of Dormant and Active Cambium of Conifers

Abstract

The cambium of SUGI (Cryptomeria japonica D. DON) and KUROMATSU (Pinus Thunbergii L.) with its dormant and active state were compared on the ultra-structural level after glutaraldehyde-osmium tetroxide fxation. The characteristics observed in the dormant cambium are as follows. 1. The organelles are densely and uniformly distributed throughout cytoplasm. 2. Comparatively many vacuoles are present and they are small. 3. Vesiculated smooth ER are rich, although rough-type ones are sometimes observed. 4. Amoeboid type plastids.can scarcely be seen. 5. Reserve substances such as starch granules and lipid droplets are comparatively abundant. In contrast to the dormant cambium the active one is characterized as follows. 1. Cytoplasm is localized at the periphery of cambial cells. 2. Cytoplasm is occupied by a large vacuole. 3. A number of rough ER are present. 4. Amoeboid type plastids are frequently seen. 5. Starch granules and lipid droplets are few. In addition, cytological differences between SUGI and KUROMATSU are as follows. The cambium of SUGI is characterized by the presence of intralamellar inclusion of some plastids in the dormant state and of phytoferritin of plastids through both states, whereas the cambium of KUROMATSU is characterized by the presence of numerous reserve substances, especially lipid droplets, in the dormant state.