What do pine cones and paintings have in common? A 13th century Italian mathematician named Leonardo of Pisa.

This undated photo shows a spruce cone with a marked fibonacci number sequence. A numbers sequence thought up by the 13th century Italian mathematician known as Fibonacci plays out in plants, from pine cones to pineapples. (AP Photo/Lee Reich)

Better known by his pen name, Fibonacci, he came up with a number sequence that keeps popping up throughout the plant kingdom, and the art world too.

A fibonacci sequence is simple enough to generate: Starting with the number one, you merely add the previous two numbers in the sequence to generate the next one. So the sequence, early on, is 1, 2, 3, 5, 8, 13, 21 and so on.

Numbers and plants

To see how it works in nature, go outside and find an intact pine cone (or any other cone). Look carefully and you'll notice that the bracts that make up the cone are arranged in a spiral. Actually two spirals, running in opposite directions, with one rising steeply and the other gradually from the cone's base to its tip.

Count the number of spirals in each direction—a job made easier by dabbing the bracts along one line of each spiral with a colored marker. The number of spirals in either direction is a fibonacci number. I just counted 5 parallel spirals going in one direction and 8 parallel spirals going in the opposite direction on a Norway spruce cone.

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