This is a vine found in Portugal and the Mediterranean. (It reminds me of Morning Glory). It is quite invasive and manages very dry conditions. The flowers close in the evening. They have a paper looking quality. As they grow older they seem to develop white stripes. These ones are growing on a wire fence around a small casa. They have been allowed because they are very pretty and they do offer shade to other vegetables.
I have searched for the botanical name without success but they are commonly called the wild purple Lilly Vine.