I have done a little detective work on the AHS registered database,
Doorakian registered six diploid daylilies up to and including 2003 and they were all registered as semi-evergreen.
He registered 17 diploid daylilies from 2004 until this year. There were 16 dormants and one evergreen.
One might wonder how that can be. Perhaps, he no longer uses semi-evergreen in registrations, in which case the dormant category might include both.
Putting that thought aside, we can look at what little is known about growth categories in daylilies. The registration categories for "foliage" are for mature plants so dormancy relates to daylily growth. Seed dormancy categories can be and probably are different from foliage categories.
Stout found that evergreen was dominant to dormant in crosses of diploids. If daylily genetics was simple and if he meant completely dominant and if dormancy/evergreen was determined by just one gene then dormant diploid plants would be dd and evergreen diploid plants would be Dd or DD.
In that case a dormant x dormant cross (dd x dd) could only produce dormant seedlings.
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Now unfortunately I have to introduce a serious problem - what exactly does dormant mean?
It means that the plant stops growing. But it means that particular parts of the plant stop visibly growing. Those parts can stop growing for three different types of reasons. One is that the conditions become poor for growth (called ecodormant), another is that another part of the plant forces the stoppage (called paradormant) and the third is that the part itself determines the stoppage (called endodormant).
Stout looked at dormancy in daylilies. He found that most daylilies (in those days) were only ecodormant but a few seemed to be endodormant. Those that were endodormant seemed to be of perhaps two types. One type would die if the dormant plant did not experience some cold and the other type would start growing again after a delay of some time at warm temperatures without experiencing any cold.
I have been looking for modern daylily cultivars that go dormant and will not start growing again unless they experience some cold (some call these hard dormants). So far all those that I have tested because it was thought they might be hard dormants have started to grow without experiencing any cold.
Researchers have tested some daylily cultivars and they did not find any that required cold. Doorakian wrote an article for the Daylily Journal on growing daylilies hydroponically in greenhouses and his plants (half of which were considered dormants) did not experience cold and did not require it.
Now there is another thing that might affect how daylilies grow in various regions.
'Dormants' tend to be hybridized in the North or where there are colder winters; 'evergreens' tend to be hybridized in the South or where there are milder winters.
Arisumi ( a researcher with the USDA) looked at forcing daylilies to flower at a time that was not normal. He grew daylilies at several temperatures, 55, 65, 75, 85 and 95F. He found that the daylilies " At 85° and 95° the plants grew rapidly during the first 3 to 4 weeks and then became progressively chlorotic and the older leaves dried prematurely". He also found "At 85° most of the flower buds were blasted and only a few misshapen flowers bloomed. The scapes were weak and about half the size of those formed at 75°."
He did his research in 1960. It seems that daylilies did not appreciate growing at high temperatures.
No matter where one hybridizes one always selects/adapts ones plants to the conditions present in that location. Dormants hybridized in the North will not only be adapted to colder winters but also to cooler summers, shorter periods of heat, etc. Evergreens hybridized in the South will not only be adapted to milder winters but also to hotter summers, longer periods of heat, etc.
'Dormants' might not do well in some locations in the South because they are adapted to cooler growing conditions rather than the lack of cold in winter.
Now to introduce another complication.
Plants grow in one location - they cannot move around like animals and choose better places to grow. Plants have to adapt to whatever conditions they find themselves in (called phenotypic plasticity). They can change their behaviour.
This last year I grew Ophir in three different locations with different conditions.
In one location (grew there for 15 years, no fertilizer, only rainwater, rarely weeded, not divided) Ophir acts dormant from early summer (ecodormant because it grew immediately when brought inside on Oct 18 one year).
In another location, (grew there for one year, fresh garden soil, no added water or fertilizer, grass sod was turned under, no weeds) it grew like an evergreen during the year but by mid-late autumn appeared dormant.
In another location, (grew there for one year, fresh garden soil, added water and fertilizer, no weeds) it grew like an evergreen right up to the time that its leaves were killed by the cold.
Whether a cultivar is dormant or evergreen not only may depend on where it is grown but also on exactly how it is grown.
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Can a registered dormant x registered dormant cross produce evergreen seedlings, semi-evergreens and/or dormants. I would say yes, but it might produce more dormant seedlings than other types. How well those seedlings grow in specific locations might depend more on where their ancestors were hybridized than their registered foliage type.
Maurice
