The head of the sunflower exhibits a great number of equiangular spirals with common centre. We know that the spirals exhibit self-similarity, but does the head as a whole? Consider the circle that encloses the spirals. If we now take a slightly smaller concentric circle we can rotate it slightly about the centre to make the spirals within the two circles align (see diagram at right). This gives self similarity within a certain range, and so the sunflower is a fractal structure.
S4. SUNFLOWER
