The Fibonacci series crops up in a number of natural structures, such as phyllotaxis (the arrangement of leaves on a stem), pineapple fruit sprouts, artichoke flowering, an uncurling fern, the arrangement of a pine cone, etc.
In this table:
Each branch bifurcation point coincides with a consecutively smaller Fibonacci number, as shown in the following image:
As can be seen, the innermost circle's diameter is proportional to the Fibonacci number 21 whereas the outermost circle's diameter is proportional to 21 + 13 + 8 + 5 + 3 + 2 + 1 = 53; where 1, 2, 3, 5, 8, 13, and 21 are the first seven "useful" values of the Fibonacci series.