This Greek word for 'leaf arrangement' is a mathmatical sequence that is found in nature. The angle between leafs on a stem is constant. Leafs need to get a maximum amount of sun, therefore the above leaf needs to block as least sun as possible. This is done with the golden ratio. The golden ratio is approx. 1.618 which translates to about 137.5°. It can be found all through nature, from pine cones to flower petals.