Recently, a 13year old kid has re-dicovered that there is a magic ratio for branching in plants. Following article describes his work in his own words.
In 1754, a naturalist named Charles Bonnet observed that plants sprout branches and leaves in a pattern, called phyllotaxis. Bonnet saw that tree branches and leaves had a mathematical spiral pattern that could be shown as a fraction. The amazing thing is that the mathematical fractions were the same numbers as the Fibonacci sequence! On the oak tree, the Fibonacci fraction is 2/5, which means that the spiral takes five branches to spiral two times around the trunk to complete one pattern. Other trees with the Fibonacci leaf arrangement are the elm tree (1/2); the beech (1/3); the willow (3/8) and the almond tree (5/13) (Livio, Adler).
I'm facing difficulty in understanding highlighted statement. He says fibonacci fraction for 2/5 means that spiral takes five branches to siral two times around the trunk.
Implies, Angle between each branch is 720/5 = 144 degrees.
But the kid says,
The pattern was about 137 degrees and the Fibonacci sequence was 2/5.
What am I not understanding?