A couple of years ago, after having tried for nearly ten years to get Petrocosmeas to set seed, I made yet another attempt. Due to impending long days and heavy weeks ahead with my shifts at work, I had placed several of my Petrocosmeas that were showing buds underneath a humidity dome in my basement light stands. In early October, two species were sitting side by side underneath one of those domes, and both were in flower. P. rosettifolia #3 and P. sericea. So, on a whim, I took the pollen from both flowers and made reciprocal crosses between the two species. I then put it out of my mind, assuming, as had always been the case, that both would fail. A month or so later, when I had a chance to check on my plants in between shifts, I noticed seedpods forming on both species!!! WHAT?!! It couldn't be! But, yes, there they were...five seedpods... three on the rosettifolia and two on the sericea! I don't recall how many flowers on each species I had pollinated, but some had indeed worked. Sixty-seven days later, I harvested the seedpods from P. rosettifolia, and then about two weeks after that, the seedpods on P. sericea were harvested. There were seeds inside of all of them.
Eight months after sowing the seeds, the first seedling from the rosettifolia x sericea cross flowered...it was on what had been the most vigourous seedling all along....that plant later was named P. 'Rosemary Platz' after a dear friend. That first year, the plant had five flowers, but the foliage was really nice, and it shaped up very nicely.
Petrocosmea 'Rosemary Platz' in it's third season of bloom...now a mature plant. It has exceeded my hopes and represents three qualities that have now become standards that I select for in all of my Petrocosmea hybrids.....floriferousness, reluctance to form offsets, and attractive, ornamental foliage.
A mature plant of P. 'Rosemary Platz' just coming into flower. This hybrid has attractive foliage, showing the glossiness and lighter yellow veining of it's P. rosettifolia #3 parent. It gets it's leaf shape and size from it's P. sericea parent. An additional plus is that after three seasons of bloom, the original plant has never yet formed a single offset...a trait that I select for in my hybrids. The tendency to offset at flowering ruins many showplants...and is a nasty trait of the P. rosettifolia species used as a parent. P. rosettifolia #3 is the form with yellow veining that is least likely to offset. Form #4 offsets very heavily and is the form of this species that, for me, is the most reluctant to flower. By chance, I used form #3 in this cross.....that was purely an "accident"...but was a happy "accident".
My friend and hybridizing mentor, Dale Martens, took this photograph of a dissected flower of P. 'Rosemary Platz'. This photo shows the attractive purple stigma at the tip of the pistil, and the feathery white furriness of the filaments supporting the anthers.... both traits that neither of this hybrid's parents have. SO where did these traits come from???? ("Thank you" Dale, for allowing me to use your photograph!)
As my third year of Petrocosmea hybridizing comes to a close, I've been very happy with my first hybrid. I've been delighted at the response I've gotten from Petrocosmea growers and gesneriad enthusiasts in general about this hybrid and I hope that it will become a welcomed addition to the world of gesneriad hybrids. This year, I've attempted to take things to the next generation, as I've begun using P. 'Rosemary Platz' and it's siblings, as parents in new crosses. They are now forming seedpods....indications that they may be both pollen and seedpod fertile. I'm excitedly looking forward to the future to see how my "child" behaves as a "parent".