Ginkgo Golden Number
The golden number or ratio (phi) is an irrational number, approximately 1.618 033 988 749 894 848, that possesses many interesting properties. Shapes proportioned according to the golden ratio have long been considered aesthetically pleasing in Western cultures, and the golden ratio is still used frequently in art and design, suggesting a natural balance between symmetry and asymmetry. The knowledge of the Golden Number also existed in old cultures worldwide. i.e. Aztec, Egypt and Tiwanaku.
More info about the golden ratio can be read here.
Carlos Calvimontes Rojas sent me these pictures in which he shows the golden number in the leaf of Ginkgo biloba.
He has several websites about this subject in English and Spanish:
Geometry of the parabola according to the golden number and Geometria de los exapenta and Medidas Sumerias-Sumerian Measures and Puerta del sol de Tiwanaku.