Petrocosmea 'Keystone's Barnswallow' - the flowers are deep blue/purple with a white halo effect at the base of the upper two petals and two yellow lines in the throat. Having an opportunity to introduce one's own hybrids is always great fun. I'm excited to be able to introduce a new Petrocosmea hybrid - Petrocosmea 'Keystone's Barnswallow', the happy result of a cross utilizing the new Japanese hybrid 'Asa Blue' as the seed parent and the species P. begoniifolia as the pollen parent. From the very beginning this has been an exciting hybrid cross!
The cross was exciting for a number of reasons. First, it was a Petrocosmea cross, that alone is exciting, since there have been so few! Hybridizing Petrocosmeas, while I've been fortunate to have some success, has not been easy. Sixty seven percent of the time, I fail to produce seeds when I attempt a Pet cross. Secondly, though, this cross in particular was a breakthrough because it utilized a Pet hybrid as a parent. I believe it may be the first successful Pet hybrid utilizing a hybrid as a parent, ever! The few that have been made, so far, have always been primary crosses between two species. This cross proved that at least some Petrocosmea hybrids are fertile. It is only the second cross, that I am aware of, that utilized P. begoniifolia as a parent. I was interested in using this species because it has white flowers, it has yellow in the flower, and it has purple pigmentation in the leaves and pedicels and peduncles as well as the the calyx lobes. I felt that introducing purple pigmentation into the plant's various parts would be an exciting characteristic of hybrids. So, there were lots of high hopes for this cross...and it has exceeded my hopes!
The cross produced two full seedpods and lots of seed. I had good germination, and from the early stages, I could see a good deal of variation in the leaves on the baby plants. The cross has P. begoniifolia, nervosa, and flaccida in it's background, and among the 30 seedlings that I am growing out, I can see plants with dominant features of each of the three species in the foliar characteristics. I was very happy to see that many of the plant began to bloom at an early age, and for young plants, are still producing lots of buds and flowers. This definitely comes from the 'Asa Blue' parent, which blooms heavily, over a long period, and blooms as a quite young plant. The plants are taking on a very pleasing leaf symmetry and shape from a very early age.
A photo of the whole plant. This photo shows P. 'Keystone's Barnswallow' in a three inch pan pot. Foliage is showing a bit of chlorosis in the photo due to the plant being placed on shelf with new T-8 lights and getting a bit more light than it likes, however prior to this, the plant had lovely deep green, glossy foliage with the nice pebbling effect that begoniifolia has. Flowers are a pleasing contrast of deep blue against the green foliage. There are still lots of flower buds underneath those leaves!
A photo of P. 'Asa Blue', the seed parent of my cross. P. 'Asa Blue' is a remake of the cross that produced P. 'Momo' the first Pet hybrid. The cross is P. flaccida x nervosa. 'Asa Blue' produces flowers of a medium to light lavendar, while 'Keystone's Barnswallow' has much darker blue/purple flowers that hold the deep color until they fade. 
The pollen parent for 'Keystone's Barnswallow' ...the lovely species P. begoniifolia. I chose it in the hybridizing effort because of the flower shape, it's white color, with yellow in the throat, and the purple pigment in the calyx lobes and pedicels as can be seen in this photo. The cross has produced a lot of good flowers, but several have been discarded as "nothing new". I have selected five so far to keep and evaluate further. P. 'Keystone's Barnswallow' is surely the best so far. Across all of my hybridizing efforts, I am selecting seedlings for two qualities in general.... 1) early, and prolific flowering across a long period, 2) attractive, ornamental foliage that shapes well and does not tend to offset easily. With individual crosses, I may have other goals. This new hybrid I feel, meets both goals. 'Keystone's Barnswallow' began flowering in early June and has been in continuous flower ever since. It has at least 15 more buds that I can count underneath the foliage. And, while several of it's siblings have formed offsets, it has not and shows no sign of doing so at this point.
