Phyllotaxy is the arrangements of leaves and flowers on a plant stem.

Spiral phyllotaxy is one of the main types and is caused by the accumulation of the plant hormone auxin in sequence 137.5 degrees away from the last accumulation site on the meristem. This is the Fibonacci sequence. (Correct me if I’m wrong. This is from a lecture by Mark Estelle, UCSD Professor, on 2/21/12)

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