I do respect everyone's experience and the right to decide for one's self, but do hope that you will do your own research, and take any possible ill effects seriously if anyone has them after eating - some research does seem to indicate that there may be some toxins, and potential health effects, from eating daylily parts. It does seem that you really could eat some of the daylily products for an entire lifetime and not have any problem, but that toxicity can and does crop up without warning. In their region of origin, Asia, daylilies are eaten more frequently than in the West, and research there still appears to claim that there may be serious toxins, for example, even in the daylily flower. However, there are also further posts below that will help to explore and open up that research to more questioning. So, the rest of this particular post will be couched in more tentative terms (with regard just to daylily flowers) and is only a caution of them that you can sort out to your own level of trust.
Regarding rhubarb leaves, they were also originally thought to be harmless, until the Army began using them to feed troops in WWI. Only after they became more widely consumed in that way did they then realize toxins were causing problems and deaths. Likewise, potatoes can be toxic, if green or sprouting tubers are not handled or cooked correctly. The same may be true for the daylily as it is for wild mushrooms, or uncooked meats, and so forth.
Daylily flowers, it has been claimed in the East, may have naturally occurring Colchicine in them and:
"Colchicine poisoning is an uncommon,
but potentially life-threatening toxicological emergency that has
the potential to cause multisystem organ failure." -- see the second link, below
These purported Colchicines in daylily flowers (which would, seemingly, include all daylilies, not just tetraploids - and including older species daylilies) have been said to be a naturally occurring chemical in the flowers that are used in culinary dishes. This has prompted some researchers there to look for safe cooking techniques and handling recommendations, especially for home cooks, in order to reduce potential problems that may occur.
Two easy to read articles about those daylily food-handling techniques and health safety guidelines are at:
http://www.articlesbase.com/he...
http://world-food.net/download...)
So, it may be wise to keep some caution and guidelines in mind, just as we all would with rhubarb, potatoes, wild mushrooms, and undercooked meats:
1) Hybrid daylilies (daylilies called by common, non-latin names, like Happy Returns, etc) may be better plants for viewing, but they have never been recommended for eating - only older species with latin names have been said to be edible (see Tink3472's post and link above). And, species plants were imported from Asia, so they would likely still have the same composition as those that some research indicates may possibly contain toxins (and be the cause of some problems);
2) Daylily roots/tubers (and possibly leaves) can contain toxins that, even after eating them over a long time with no side-effects, can still result in poisoning, since it is not possible to easily know when, or under what conditions, the toxins will be present (see Admmad's posts and links above) and;
3) Per the Asian research (linked above) daylily flowerd should be handled with care. The links go to articles describe blanching and rinsing techniques (the first link), and safe storage, pickling and blanching times/temps needed to process raw daylilies as reported by the 2013 paper (the second link), from research that was done in an effort to address health problems believed to be occurring in Asia. They note that possible daylily flower toxins may actually increase at some temperatures used in food storage and preparation (39-86 degrees fahrenheit). Time-trial tests with commercial (forced-)air drying ovens (different than our home ovens) reduced their measurement of toxins by less than 50%, and home baking ovens were not recommended or reported in the study.
4) Medical centers may not be aware of possible daylily toxins (accepted or questioned) if presented with a patient's gastrointestinal symptoms, or the potentially more critical and acute conditions that might rapidly unfold, perhaps especially since daylilies are so infrequently used as a food source in the US. Consider printing out and bringing the noted and linked findings if a bad reaction follows after deciding to eat daylily parts.
