  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.
