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Scientific Term for the Arrangement of Sunflower Seeds in the Head of a Sunflower

Two scientific terms are associated with the patterns in the head of a sunflower, the leaflets of a pine cone, and other patterns that seem orderly in nature. However, neither the "golden ratio" nor the Fibonacci sequence of numbers from which it is calculated is magical, as nature's perfection is affected by many random factors.

Golden Rectangles and Spirals
- Some ancient Greek builders used rectangles with a ratio (the longer side divided by the shorter side) of 1.6180339887. If you make a spiral nest of smaller and smaller golden rectangles and draw a logarithmic arc to connect their diagonal corners, you wind up with a pretty good approximation of the spirals of some mollusk shells, plant centers and other orderly designs in nature.
Fibonacci Sequences
- Leonardo of Pisa, also known as Fibonacci, was an Italian mathematician circa 1170 to 1250. He discovered sequences of numbers that are formed by adding neighboring integers, e.g., 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144. He also found that dividing a number in such a sequence by its next smaller neighbor, after the first couple, produced the golden ratio.
Why They Grow That Way
- The flower parts that are pollinated to form seeds in a sunflower grow from the center, each pushed a bit by the next as the flower head forms. An arc measured by the golden ratio (or its inverse, 137.5 degrees) just happens to describe the most efficient way for the seeds to pack together as they grow.

Nature