Smoky blue, violet, mauve then grey. The colour changes as the delicate flowers unfurl, bloom and fade.
The colour changes as clouds or leaf shadows move across the sun; it changes with the angle of the sun as you move your head from side to side.
To a bee the base colour of the petals is probably irrelevant. What matters is those guide lines leading to the honey.
But to a human eye the changeability of these fragile petals is part of their fleeting beauty.
And for those who’d prefer facts to poetic meanderings, this is a cultivar of Hibiscus syriacus called ‘Ultramarine’, growing in a pot in our small Paris garden.