Iris.hexagona is the one Louisiana species that I have not observed anywhere in Louisiana. The reason I ventured on a two week search for irises throughout Florida was curiosity stimulated by what I read in the Society's Fiftieth Anniversary publication of 1991.Throughout the small book, especially in articles by Dr. John K. Small reprinted from the 1930s, Florida cities and towns were mentioned as the location of many of the then-designated species of irises.
These irises are now classified as I. hexagona, although some do recognize I. hexagona savannarum as a separate variety within the species I hexagona. (I.savannarum was one of the old, discarded species names). Even though all the East Coast irises are today considered to be i.hexagona, there had to have been sufficient variety among them to induce Small to extend several different species designations.
On a Florida map, I highlighted all the places mentioned in the book and planned the best routes to visit each one of them. I found and collected samples of irises in all the sites, except the white i.albispiritus that was reported to be near the Caloosahatchee east of Fort Meyers. The book described the location to be about 12 miles up the Caloosahatche River but, I could not secure a boat to reach this site. On my trip through the interior of Florida I saw the variety I. hexagona savannarum growing in moist soil in very large fields of several acres. These fields did not appear to hold water so the irises grow under conditions similar to I.brevicaulis in Louisiana.
In most of the sites in Florida, the irises were growing next to canals, ditches and streams, similar to the places where I.fulva is found in Louisiana. Irises do not occur in the Everglades. Overall, the Florida irises do favor I.giganticaerulea in many ways, but with some differences. The forms I saw are shorter, their color generally is a darker blue, and the leaves appear to be stiffer. I did not see a single white iris in Florida on either of the trips there. The largest color difference is in the irises on the west cost of Florida in Dixie and Levy counties. The irises there are the darkest blue I have seen, darker than any i.giganticaerulea that I have encountered in Louisiana.
The shorter height of the Florida irises compared to I.giganticaerulea could be due to the soil. Florida has a siliceous sand, coarse base, while Louisiana has a rich black mud. This appears to be the most significant environmental difference between Louisiana and Florida, and it could account for the smaller size of Florida irises. There is a good deal of variation among the Florida irises, but I leave it to the experts to determine whether they should all be lumped into I.hexagona. I personally did not find enough variation to warrant the naming of new species.
It is difficult to make a direct comparison of Florida and Louisiana specimens under like conditions. The performance of Florida irises in Louisiana is very poor for the first year or two, and then they seem to acclimate and begin to bloom. Perhaps in time there will be a better basis for conclusions.