Hi Eckhard- The seed for the Y. gloriosa came from a friend in Tennessee (from large trunking plants)- I selected from ~100 seedlings, and have perhaps 15 left now. I would not be surprised if the plants that have survived have more flaccida/filamentosa genes than those that perished. The first picture shows that the branching is happening right next to the flower point, as opposed to suckering from the ground. Will be interesting to see how/if they grow trunks.

I think that the cross of the elata hybrid is by Jurgen Bredow- filamentosa 'kaktusgarten' x elata "White Sands"

The coldest my garden has seen is -32C, with many years in the -28C to -30C area. The cold lasts months, and in cold year we can have weeks at a time that do not see temps above freezing. I think last year was very mild and we hit -26 or -28C but the cold was not persistent. The only protection my plants get is to have the spears tied into a point- this prevents the 'flattened' look that Yucca get in very snowy climates.

Sure, lets exchange some seeds! My email is attached.