'Ed Murray' (EM)
Ed Murray was considered to be sterile. It is not a triploid to the best of my knowledge as someone did do a chromosome count of its roots and found approximately 22 chromosomes rather than 33. The approximate is because some of the chromosomes did not spread out well for them when they spread them for the microscope and so were probably on top of each other.
Ed Murray was converted to tetraploid by at least one hybridizer and possibly more than one.
However, the hybridizer who converted it then learned about something called 'unreduced gametes' or '2n gametes' which diploids can sometimes make.
Unreduced gametes
A diploid has 22 chromosomes. When it makes pollen or ovules (its gametes) it reduces that number to one-half for both the pollen and the ovules. So the pollen and ovules have 11 chromosomes. When the two gametes combine, the seedling gets 22 chromosomes as it should to be a diploid.
Sometimes in making the pollen and ovules mistakes happen and instead of having 11 chromosomes they end up with 22 chromosomes. The mistakes are rare and some plant species make more mistakes than others. Very high temperatures and very low temperatures when the pollen and ovules are being made cause some of the mistakes. Others are caused by the plant being a mutant and simply having a faulty mechanism for making pollen or ovules or sometimes both. Pollen or ovules with 22 chromosomes (the normal diploid number) are called unreduced gametes because they should have had 11 chromosomes or the reduced number.
Sometimes a diploid flower will have lots of normal pollen (11 chromosomes) and a few unreduced pollen grains (22 chromosomes). Sometimes if one of the unreduced pollen grains is successful with a diploid ovule a triploid plant will be produced. So unions of unreduced gametes with normal diploid gametes are thought to be how triploid (33 chromosomes) daylilies were created naturally.
If an unreduced gamete (22 chromsosomes) from a diploid joins with a normal gamete (22 chromosomes) from a tetraploid then a normal tetraploid (44 chromosomes) seedling will be formed.
The hybridizer who learned about unreduced gametes then thought to try the normal EM with tetraploids. He produced some seedlings. He then changed his mind about the success of his converted tetraploid EM and decided it had not been converted successfully. Some people selling converted EM as a converted plant then seem to have dropped the converted description. The end result was that buying Ed Murray was a gamble. One might be receiving the diploid or a possibly converted tetraploid.
Ed Murray is able to produce unreduced gametes. When its pollen is looked at under a microscope its size is best described as 'giant' - it is much larger than a normal diploid's pollen. That is what should be the case since size in plants depends usually on the number of chromosomes and normal tetraploids have larger pollen than normal diploids.
Many hybridizers then used Ed Murray with tetraploids and produced tetraploid introductions. It is not known whether some, most, all or none of them used the diploid version or a treated possibly converted tetraploid version.
The complications do not end.
The verdict for EM's sterility at the time when there was much discussion was that EM was not fertile with diploids but was fertile (a little) with tetraploids. What about the diploid registrations from EM? I don't know anything about 'Jupiter Lighthouse' or 'Bangladesh'. But it turns out that 'Thornbird' is not a diploid; it is a tetraploid. People have looked at 'Little Grapette' pollen and I believe repeated the cross but were not successful in producing seedlings and did not find 'giant' pollen. That caused some to decide that 'Little Grapette' was not the pod parent but that 'Little Grape' was a possible pod parent and the registration was in error. 'Little Grape' is a tet while 'Little Grapette' is a diploid.
Some people have suggested that unreduced gametes be used instead of converting diploids to tetraploids. However, Arisumi looked at how frequently daylilies produce unreduced gametes and it is very rare and not practical for daylilies. He produced 2 tetraploids from several thousand pollinations. Of course those pollinations must be done in insect-free conditions so that there is no chance that natural pollinations occur. That is, the cross would be tetraploid x diploid (to use unreduced gametes to produce a tetraploid seedling) and one must be certain that no tetraploid pollen can land on the stigma. One also must check the number of chromosomes in any seedlings that are produced since it is approximately 15 times more probable that they are triploids than they are tetraploids.
In my growing conditions I find that EM pollen usually looks sterile but it seems to look better and possibly be more fertile when the weather has been very hot. Unfortunately, that does not happen here much. The Ed Murray I grow does rarely set a mature pod after I pollinate all its flowers (clump) and I have seen a single seed in such pods that looks normal. I have never bothered to plant them.
