Summer flowers and some mathematics

What wonderful flowers sunflowers are...........
They seem to be a great symbol of summer.
So yellow...
So bright....
So large....
Even Delia Smith uses it on her summer cookery collection.
What is usually called the flower is actually a head of numerous florets (or small flowers) crowded together. there are actually two sorts.
The outer florets are the sterile ray florets and can be yellow, maroon, orange, or other colours. The florets inside the circular head are called disc florets, which mature into seeds.
The florets within the sunflower's cluster are arranged in a spiral pattern. Typically each floret is oriented toward the next by approximately the golden angle, 137.5°, producing a pattern of interconnecting spirals where the number of left spirals and the number of right spirals are successive Fibonacci numbers.