We report a practical method to assign parastichy numbers to spiral patterns formed by sunflower seeds and pineapple ramenta using a discrete Fourier transform. We designed various simulation models of sunflower seeds and pineapple ramenta and simulated their point patterns. The parastichy numbers can be directly and accurately assigned using the discrete Fourier transform method to analyze point patterns even when the parastichy numbers contain a divergence angle that results in two or more generalized Fibonacci numbers. The presented method can be applied to extract the structural features of any spiral pattern.

Sunflower florets spirally fill an inflorescence. Parastichy pairs are a great indicator to understand condition of seeds arrangement. The Parastichy pairs can be calculated as two peak values by the discrete Fourier transform (DFT), from point distributions previously simulated. The most realistic Parastichy pairs obtained by reapplying the two peak values to actual sunflowers can be used to understand and evaluate the sequence of the sunflower seeds.