Acta Societatis Botanicorum Poloniae
Historically, the study of phyllotaxis was greatly helped by the simple description of botanical patterns by only two integer numbers, namely the number of helices (parastichies) in each direction tiling the plant stem. The use of parastichy num- bers reduced the complexity of the study and created a proliferation of generaliza- tions, among others the simple geometric model of lattices. Unfortunately, these simple descriptive method runs into difficulties when dealing with patterns pre- senting transitions or irregularities. Here, we propose several ways of addressing the imperfections of botanical reality. Using ontogenetic analysis, which follows the step-by-step genesis of the pattern, and crystallographic analysis, which reveal irregularity in its details, we show how to derive more information from a real botanical sample, in particular, about its irregularities and transitions. We pres- ent several examples, from the first explicit visualization of a normal Fibonacci parastichy number increase, to more exotic ones, including the quasi-symmetric patterns detected in simulations. We compare these observations qualitatively with the result of the disk-packing model, presenting evidence for the relevance of the model.
phyllotaxis, Fibonacci, quasi-symmetry, disc-stacking model, irregular pattern
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Douady, Stéphane and Golé, Christophe, "Fibonacci or Quasi-Symmetric Phyllotaxis. Part II: Botanical Observations" (2016). Mathematics and Statistics: Faculty Publications, Smith College, Northampton, MA.