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Spirals

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Such flat rosette plants from the family Crassulaceae (thick leaf plants) (here probably Aeonium spec.) can be found on nearly all vertical rocks on the canaries and Madeira.

Fibonacci spirals

Many plants form spirals with their leaves or homologous organs as scales, fruit leaves etc.. Examples known by everybody are cones, sunflowers or pineapples. If one counts the spirals in each direction on this picture, one sees 3 (red) and five (blue) spirals. This isn't by accident. In about 95% of all cases the numbers of spirals in each direction are two successive numbers of the Fibonacci sequence

1, 2, 3, 5, 8, 13, 21, 34, 55, ...

in which every number is the sum of the two preceding numbers. The remaining cases mostly come from the analogously formed "Lucas sequence"

1, 4, 5, 9, 14, 23, 37, 60, 97, ...

This sounds a bit like number mysticism, but in theoretical biology under the subject "phyllotaxis" there are several rather plausible theories, which can explain this.



Homepage(2)     Plants(index) by Michael Becker, 3/2002. Last modification: 11/2003.