2
Fig 7
The campanula [Fig 7] provides a more complex example of mutual repulsion. It is a plant which usually bears a 5 lobed flower. There are many instances of numbers from the Fibonacci series occurring in plants. But that doesn’t mean that a plant exhibiting elements in groups of 5, for instance, necessarily has a connection with the series.

Not every 5 is a Fibonacci 5.
The Fibonacci 5 is irrationally symmetrical, as are all iterations of 137.5...° [see Fig 23, cyberflowers], whether or not the number of elements is a Fibonacci series number. But Fig 8 shows it is not regular as so many 5 petalled flowers are.
Fig 8
Fig 9
Sometimes a campanula flower has 4 lobes, sometimes 6, sometimes 7. But in each case the shape formed [Fig 9] is regular, whether quadrilateraloid, pentagonoid, hexagonoid or heptagonoid.
Mutual repulsion of the primordia provides an explanation to fit all cases, because flowers with different numbers of lobes appear on the same plant and share the same genes.
Fig 10
In contrast with these regular shapes, Fig 10 shows iterations 4 - 7 at 137.5°.
It is sure that the campanula cannot be using a perceived angle of 72° or 144° because both of these repeat after 5 iterations. Coping with one or two extra primordia, or with one fewer, is not a problem if they mutually repel one another. But an upper limit is probably not too distant.
Fig 11
The use of a perceived angle provides another morphological solution. It too had a limiting factor. The angles, however they vary as a result of differing sensitivities to light, would be acute. The first 5 iterations of 42.5...°, the supplementary angle to 137.5...°, for example, would look like Fig 11.
The blackberry's answer to the problem, shared with many other plants, comes next.