14 DAY TRIAL // Have you noticed that many plants grow in spiral?
The pineapple, for example, can have 8 scale spirals headed into one direction and 5 or 13 headed towards the other direction. If you look at the seeds of the sunflower, you will see at least 55, respectively 89, spirals crossing each other.
The cauliflower also displays spirals.
Why do plants grow this way?
Does the number of the spirals have any significance?
You should know first that plant organs, like stem, leaves and flowers, grow from a central growth point called meristem. Every new structure, named primordium, develops from this center, growing to a new direction and forming a certain angle with the previous primordium. In most plants, the primordia grow at a certain angle one towards another, so that their disposition is in spiral.
What value does this angle have?
Imagine you have to project a plant around a development point so that the primordia are located compactly, without wasting space. Let's say that each primordium grows at an angle equal to two fifths of a cycle. The problem is that each fifth new structure would grow exactly on the same place and direction.
This way, they would form rows that waste space. In fact, any finite fraction of a cycle would dispose the primordia in rows, wasting space. Only a "golden angle" of 137o 30' would form a compact disposition for the primordia.
Why is this angle unique?
It's ideal because it can not be expressed by a finite decimal fraction of a cycle. 5/8 tends to the golden angle, 8/13 even more and 13/21 much more but none can express precisely the golden angle.
That's why when a new primordium develops following the golden angle, there will never be two primordia growing in the same direction. Instead of forming radiuses from the central stem, the primordia form spirals. Computer simulations of the primordia' development from a central point achieve visible spirals only when the angle between the new primordia approaches more to the golden angle.
The effect is lost even with a just one tenth of a degree deviation from the golden angle.
The number of spirals resulted by the development of the plants following the golden angle is a number from "the line of Fibonacci".
This line was first mentioned by the Italian mathematician Leonardo Fibonacci during the XIII th century. In this progression, each number is the sum of its previous two numbers: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55 and so on. Many flowers with a spiral disposition have a number of petals from the Fibonacci line: many flowers have 5 petals, bloodroot 8, ragwort 13, chickweed 21, chrysanthemum 34, 55 or 89. Even fruits and vegetables follow the Fibonacci line. A banana has 5 flanks.
