Thanks, everyone for chiming in. I think we all know that no one person has all the answers.
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I used to be like you, Lucius. I wanted everything cut and dry, perfectly defined. Surely, if I dug deep enough, I would find the answer, and everything would be clear. Unfortunately, in botany that's usually not the case.
Even with something as "simple" as the definition of the species rank in taxonomy, the experts don't completely agree. The basic problem is that we, through our human invention of plant classification (taxonomy), try to categorize the natural world with human intellect. Nature is not a human construct, so we can only get it right as far as we understand it. From the first recorded categorizing of lilies in China as red or white lilies, to present day, our knowledge becomes more intricate, and our understanding more in depth. Taxonomies constantly change in due respect. The Flora of China project was a world collaboration, but upon "completion", it was taken over by Chinese botanists to continue the taxonomy as our knowledge grows. Many world botanists have expressed reservations about this transition. Alas it is a human problem, not a problem with nature.
It was not long ago that we had varieties of lily species based on their flower color, or tepals with or without spots. Now through DNA/RNA testing, most of these have proven not to be genetically different enough to warrant such ranking. So such rankings as L. canadensis var. rubrum, var. editorium, var. immaculatum, L. concolor var. coridion, L. formosanum var. pricei – these have been absorbed back into the type species. Even the taxonomy that this site uses (Catalogue of Life) is not necessarily the best or correct. Just as in the ancient times of human origin and all throughout history - stories, legends, and truths of the day were humanly manufactured to make sense of the natural world. Every society at every time in history had undisputable truths that later were proven false. It would be silly to think we are any different, even now. But we do our best with our "truths of the day": in this case, taxonomy.
Philosophy aside and to your point, Lucius, is pollen or stigma color alone a deciding factor of Lilium species? No. At least not in my opinion, and I have not found any evidence suggesting that color is such a steadfast characteristic that a massive genetic change would be needed (thus warranting a species designation). Sometimes, it is just the convenient way of identification, that could be right or wrong. Obviously, a species is a combination of a multitude of characteristics. Some characteristics may be 99% true across the species spectrum, others only 50% or less. That we use pollen or stigma color as a helpful determination, is useful, but only in collaboration with other characteristics.
I really don't see this as any different than color phases in animals or insects. The Flora of China only list the tepal reverse coloring as differentiating var. leucanthum from var. centifolium. (It does not recognize var. chloraster.) Nothing is said about stigma color, and the B & D photos https://www.bdlilies.com/ls255...
clearly show a dark stigma and a green (not brown) reverse tepal color. So a dark stigma is not tied to var. centifolium. And no, I would not say the photos dictate that var. chloraster has a dark stigma.
I don't have any flowering size leucanthum right now, but this is one that I grew, labeled as just L. leucanthum.
And this is a friend of mine's, also here in Minnesota.
Regarding Pontus's book, I like it very much, but he never claimed it to be all encompassing. Rather, he states clearly that his writing is biased toward his own experiences in his climate. Read with this in mind, his experience is very valuable.