This is an interesting discussion.
A few comments.
First, as to the proper spelling of the name, as a botanical species, subspecies, or varietal name it would be "swertii". Ignoring gender (this thing was named after an individual man, so we'll ignore the alternatives) the standard in botany is that if the name ends in a "hard" consonant, the ending is "ii", regardless of how it was originally published. If the name ends in a vowel or a "soft" consonant (such as y or r), there is one "i" added at the end. The name "swertii" was described as a botanical species name, so this is the proper spelling when used in this way.
Next, expounding a bit on what Robert said, the name "swertii" is generally considered (by botanists) to be a synonym of Iris pallida based on a flower color form. A botanical usage of a name applies to all plants that belong to the original population the name was described from (and the color of the flowers is totally irrelevant - if it varies within the population). So, since "I. swertii" is a younger name, and not a different species - only a form - it is listed as a junior synonym. If the name "swertii" were the oldest species name (the name of priority) for what we now call "I. pallida", everything in the wild species population would be called "I. swertii", regardless of size, color, or whatever might vary within the population; however, "pallida" is older, so we call them all "Iris pallida". Similarly, if "swertii" were the oldest name for a subpopulation (subspecies or variety) of I. pallida, it would be the proper name for that group of plants (apparently it has no such priority, so again it is listed as a synonym of the one it is supposed to belong to).
However, when used as a horticultural "cultivar name", the name need not follow any botanical rules - but there are various rules for cultivar names that various organizations have set forth. The use of a botanical name for a cultivar is almost always discouraged - it just causes confusion - yet there are quite a few very old Iris cultivars bearing names of what were originally described as botanical species. When used in this way, these names apply only to the one one "clone" (all individuals bearing the name are propagules from the same original plant; or, in another word a "cultivar"). In theory these old cultivars are supposed to be the actual original plant that the species name was described from, but in most instances is it highly likely that they are not. Regardless, the cultivar versions of the names should not be confused with the original botanical usages of the names. The Iris that is most often called Iris pallida cv. 'Swerti', may or may not be the original plant described as Iris swertii, but it doesn't matter - in practice they are two totally different and separate usages of the name. The cultivar need not even really belong to the biological population that originally bore the botanical name. It can get very very very confusing unless one remembers that the two usages are not the same. As for the spelling of the cultivar name 'Swerti', the argument has been (to my understanding) - ? - that since it was originally (in the AIS registry / checklist ??) spelled with one "i" (was it?), that is the proper spelling. I don't have a preference, and to me it's not important - I'm a botanist, and I'm a bit biased. A cultivar is an individual plant in a garden, and it has little to do with wild populations in nature and with the study of botany (unless that plant is of known provenance, in which case it is just one of many representatives of a wild species). When a name is used for a cultivar, it is different than when used as a botanical designation.
As for the hybrid origin of 'Swerti' and other plicata "I. pallida", I'm not yet convinced one way or the other. The documented man-made hybrids I've seen (including the ones Chuck posted) do not look the same as plants like 'Swerti' and 'Plicata', and clearly show their I. variegata ancestry (although, the second one is getting about as close as I've seen so far). I would suggest that if I. variegata really is the source of the plicata genes, it is most likely through past hybridization and backcrossing with wild I. pallida, and that the genes are incorporated into wild populations of I. pallida - where somebody found and collected an odd-ball plant that was named "Iris swertii". Realistically, the early date of collection of the Iris called 'Swerti' would imply to me that it was more likely to have occurred in nature, and not by chance in some garden. It could have happened in gardens too, but it just seems an unlikely scenario - to me. It would be nice to know - for a fact - if plicatas occur among wild I. pallida or not. There is so little botanical information available regarding wild Iris species (even most European ones) that it is very hard to get a real picture of what is found in the wild. Most available information regarding the genus Iris is based on and biased through limited horticultural plant collecting, which tends to focus on attention-grabbing individual plants instead of on populations as a whole. Variation tends to be ignored as a part of whole populations, and given way too much significance on an individual plant basis. Descriptions in books (especially those devoted to the genus) usually do not allow for variation, but just parrot the original descriptions and characteristics known garden plants of a given species. As one example, in the books, Iris pallida is supposed to include only plants with white spathes, but the species is clearly varied in this trait, and they can be brown or anything between white and brown. Flowers are supposed to be blue-violet, but they can clearly vary to more reddish purple hues, and to white. However, the basic morphology seems quite constant.
Of course, I would love the opportunity to study them extensively in the wild, but I'm based too far away for it to likely ever be practical for me to do so. So, I grow a few in gardens, and have to "settle".
Dave FergusonRio Grande Botanic GardenAlbuquerque
