Gross Morphology and Histology of Developing Fruit of the Apple

Abstract

1. Gross development and principal tissue changes in the fruit of the apple from 1 month before full bloom throughout the growing season to fruit ripening are figured and discussed, and suggestions are made regarding the methods and the values of measurements of various parts. 2. Interpretation of the apple as five drupelike carpels contained within the fleshy torus or receptacle has seemed to describe the structures observed. 3. The curve of gross development of the entire fruit is nearly a straight line for the early summer variety (Early Harvest), but for each successively later-ripening variety (McIntosh and Rome) the curve flattens as the season progresses. Although perhaps associated with environment, the rate of growth is shown to be a varietal characteristic, in which each successively later-ripening variety has a slower rate. 4. The cartilaginous portion of the carpels develops rapidly for 2-4 weeks after full bloom, reaching maximum size in transverse diameter the earliest of any of the tissues ...