Leaf Growth in Phaseolus vulgaris

Abstract

The growth of the first pair of leaves of Phaseolus vulgaris (French bean) has been studied during germination and following emergence of the seedling. The leaves are well developed in the embryo and, at 22.5° C, show an exponential increase in fresh weight, dry weight, and leaf area up until about eight days from planting. Cell division commences about two days after planting and is exponential for a short period. Considerable changes in cell volume occur during the period over which cell division occurs. Cell division ceases soon after emergence and unfolding, when the leaf has reached only 17 per cent of its final area. Cessation of cell division is followed by a phase of growth which is due entirely to cell expansion. The significance of these findings is discussed in relation to recent work on other genera.