Structure of the Vegetative Shoot Apex of Clethra barbinervis

This report is concerned with quantitative treatments for plastochronic changes of the apex in superficial view as a supplement to the first paper7) of the present series, which dealt with the anatomical analysis of superficial and transectional views of the vegetative shoot apex of Clethra barbinervis Sieb. et Zucc. The bases of young leaf primordia directly surrounding the apex may be expanding considerably at the expense of the area of the shoot apex. Thus, changes in area of the apex occurring during a plastochron may be intimately correlated with the expansion of the bases of young leaf primordia as well as with that of the apex itself. The growth processes, discussed anatomically in the first paper, are checked quantitatively in the present study.