I asked the RHS Advice Centre about it and this is what they said …
“This is actually a relatively common phenomenon in some plants where different parts of the plant mutate or grow into a slightly unusual part that looks out of place.
“This actually happens quite regularly in tulips with petals appearing attached to leaves and vice versa, dahlias do it often too. What with climate change and plants being pushed to the brink and suffering from all sorts of unseasonal flowering and physiological stress, I should think we will see even more of it in the years to come.
“Mother nature is essentially stressed and confused by unseasonal and extreme weather and so in plants, where in many cases many cells have the genetic material and capacity to mutate and develop in different ways, all sorts of weird, wonderful or curious things like this are possible.”