Thank you Tim. I'm hoping at least one of your hybrids could be hardy to my zone, yucca Flaccida x Filata X Filamentosa x Rostrata could be it having lots of filamentosa/flaccida genes for hardinesss and the elata/rostrata genes to make it trunk.......also my filamentosa x glauca X elata could be very hardy. time will tell, I will post pics of their progress...