Petals separating at base
The petals of one of my clematis are separating at the base before the bloom opens. Two blooms had opened as usual, but the rest are tightly closed, though seem large and mature enough to open. When I gently separated the petal tips on one flower, it instantly opened.
There is no sign of distress, disease or infestation anywhere on this plant, which I have had about 3-4 years without any problem.
I cannot recall the name of this variety, a Japanese name I think, single purple flowers with yellow anthers.