tink3472 said:
Every single daylily here is capable of producing doubles and usually do. Just like non-toothy daylilies will produce teeth at times. It is all a heat/humidity thing for us and not an unusual thing at all here. It is not a consistent thing and it may happen one year and not the next on each individual cultivar.
Thank you so much, I suspected that might be the case as someone told me that when they crossed doubles with singles the F1 was single and when they crossed the F1s together (or the equivalent crosses) they had approximately three singles to one double. That suggested that all the other genes that help the "doubling" gene to be consistent and visibly double were rampant throughout the daylily gene pool. In turn that would suggest that under the appropriate conditions most daylilies could double.
Of course, there is another interpretation - living organisms are complicated and they seldom simply obey the 'rules'. That is, all daylilies could be abnormal genetically and therefore developmentally. The end result could be that all daylilies might have developmental problems and produce double flowers under some conditions. Daylilies could be abnormal because they were produced by crossing different species, or perhaps tetraploids are abnormal simply because of their doubled chromosome sets.
Have you grown and flowered enough single flowered diploids to confirm (or not) whether they also are all able to occasionally produce double flowers?
