K writes:

It seems to me that when the flowers first open the stamens are a
creamy yellow and when they've been sufficiently visited by pollinators
they turn orange/brown

But is that a result of being visited by pollinators or is that simply
an ageing thing?

I don't know for sure, but looking again I see that a number of flowers
have a mix of lighter and darker coloured stamens (is that the right
term?) which suggests to me that something other than time must have had
an effect on the darker ones. In addition, where a flower has been
successfully pollinated, indicated by fallen petals and swelling of the
stem behind, the still-attached stamens all have the dark colouring. I
realise I may be confusing correlation with causation here but one has
to clutch at whichever straws are available.