Systematic variations in divergence angle

Practical methods for quantitative analysis of radial and angular coordinates of leafy organs of vascular plants are presented and applied to published phyllotactic patterns of various real systems from young leaves on a shoot tip to florets on a flower head. The constancy of divergence angle is borne out with accuracy of less than a degree. It is shown that apparent fluctuations in divergence angle are in large part systematic variations caused by the invalid assumption of a fixed center and/or by secondary deformations, while random fluctuations are of minor importance.

► Floating centers of divergence angle proposed. ► Indexing sunflower seeds based on a number theoretic algorithm. ► Accurate control of divergence angle is borne out with accuracy of less than a degree. ► Displacement from regular position of packed organs resembles incompressible flow of fluid dynamics. ► Systematic variation explains why only a few leaves suffice to give the mean angle close to the limit divergence.