As a comment about
Angel's Trumpet (Brugmansia 'Whitney'),
gone2seed wrote:
This cultivar is unusual in that it has produced single, double, and shredded flowers on the same plant and often at the same time. It has done this during the three-year trial period. I would normally expect a new hybrid to settle down to one type of flower after the first couple of flushes but so far, this plant is an exception. The plant may well settle later to a nice double/triple.