The Louisiana Irises belong to a group of iris species native to the American South.
The first species within this grouping to be officially described was Iris hexagona, recorded by Walter in 1788. Hence the group is today known as the Series hexagonea.
Audubon, the great painter of American birds, included the "Louisiana Irises" in the background of one of his bird paintings.
In addition to the originally described I. hexagona, other species include I. fulva (Ker-Gawler, 1812) and I. brevicaulis (Rafinesque, 1817). I. fulva brought the color red into the genetics of this group; I. brevicaulis contributed cold-hardyness.
It was not until 1929 that the tireless John R. Small described the towering blue coastal marsh iris known as I. giganticaerulea.
Still later, in 1966, Randolph described a new species called I. nelsonii--which included what had earlier been known as the "Abbeville reds."
Today taxonomists still assess (if not debate) the various species within the Louisiana irises.
From these species a myriad of hybrids--both naturally occurring and by the hand of humans--have been recorded.
I. hexagona image from the Signa Species Database and Sean Zera. I. nelsonii image from Rod Barton.