florets and the Fibonacci series

In the lab today we were talking about Fibonacci numbers. Somehow these numbers (1, 1, 2, 3, 5, 8, 13, 21, 34, …) relate to Echinacea flowerheads. The number of ray florets (aka “petals”) on ab Echinacea head are often Finbonacci numbers, like 13 & 21, but they are often not those numbers. This Wikipedia page describes the relationship between Fibonacci series and florets on flowerheads.

Here are some images of Echinacea heads from the summer (top views). Do you see any interesting patterns?