Louisiana Iris species iris.nelsonii growing int he wild near Abbeyville, LA

by Steve Shepard*

As part of my interest in Louisiana irises, I have been collecting the wild forms and species. My first attempt to collect an Iris nelsonii was a trade with a friend who had gotten the iris through an iris supplier. That plant looked like a red hybrid between I giganticaerulea and I.fulva. The fulva- giganticaerulea crossings end up intermediate with an open form and usually a rich purple or a dark purple. Usually the flower has a line signal and no halo or spray of white around the yellow signal, which is typical of giganticaerulea falls as well as the falls of I brevicaulis.

The so-called nelsonii was small-bloomed and relatively short-around three feet-straight -stalked without branches, and most importantly the style arm was typical of any crossing between fulva and giganticaerulea. The typical crossed style arm is two-lobed in cross-section with a ridge down the middle. Look at virtually any registered Louisiana iris cultivar and you will see the typical style arm.

Louisiana Iris species, I.nelsonii closeupI do not want to belabor the point that the nelsonii in question was at the least a very unexceptional nelsonii. The Abbeville swamp that contains I nelsonii at one time had a multitude of forms and colors and this particular commercially-derived plant may well have originated in the swamp but was not really the essence of what makes nelsonii different from hybrids all over Louisiana.

There are several aspects to the exceptional nelsonii: Most noticeable on the exceptional plants is a larger than ordinary flower, more toward the size of big giganticaerulea flowers. The shape of the flowers tends toward fulva with a wide, red-petaled and floppy flower, if not quite pendant. It sometimes tends more toward a stiffer, more open form, but always looking like a "super fulva".

Another noticeable trait that strikes someone who has been looking at a lot of Iris fulva in the wild, is the red color seems like a different red color. I don't know how to objectify this impression; all I can say is the red seems rich and it is postulated that there is more blue underlying the terra-cotta red of a typical fulva and this makes the plant more crimson- appearing without really being a true red or a cherry red-the kind of red we all wish were in Louisiana irises (as if the tremendous color range we already find in these plants is not enough!). Iris nelsonii can be four and five feet tall with branches and multiple blooms. This is certainly not typical of other wild forms, although certainly crosses between giganticaerulea and fulva can result in this to a lesser extent.

The trait that caught my attention the first time I laid eyes on a nelsonii that came from the heart of the Abbeville Swamp- and which seems not to existTypical example of Louisiana Iris species iris.nelsonii anywhere except in the so-called Iris nelsonii-is the "closed loop."

The style arm on the truest examples of "super fulva" from Abbeville are the same kind of round-topped, or pipe like style arms found on Iris fulva. Randolph's 1966 description of the style arm from his paper naming Iris nelsonii a new species is as follows: appendage (crest) 5-9 mm long, semi ovate, usually blunt-tipped, two-parted, margin entire or obscurely dentate; stamens partly enclosed by style arm, often protruding 1-5 mm beyond the tip of the style arm ... **

This description mostly fits the style arm description of Iris fulva, though I'm sure the measured length is usually less in most or all fulvas, since the fulva flower is so much smaller (unless influenced by introgression with I giganticaerulea).

The style arm feature described for nelsonii that does not seem to exist in any other Louisiana iris is the "partly enclosed" style arm or "closed loop."

How did this trait come about? If a plant found in or near this Abbeville swamp has an open-bottomed style arm but has every other feature of an Abbeville Red, is it a nelsonii? I would think it is not. Instead it is an offspring that has been out crossed with a less true form, or else it is an offspring that by not carrying this trait cannot be a nelsonii. In other words if nelsonii with "closed loop" crosses with itself or other closed-loop plants and doesn't produce offspring with this trait, then nelsonii is not breeding true to form, implying it is not a species.

This trait might have become common if it can be determined that nectar accumulates in a closed tube and attracts pollinators in such a way that the pollinator favors the closed loop over any nearby open loop. Perhaps this trait started as a single mutation but the feature attracted a pollinator that persisted in self-pollinating it and causing the trait to be reproduced in succeeding generations. That could also explain the trait surviving in the wild after first appearing on a single plant

Typical example of the species iris.nelsoniiI wonder why this trait has not shown up in Iris fulva? I've seen fulva style arms that approach closure on the underside in the middle but I have never seen one come close to closing the way these Abbeville reds do. Did this trait first turn up in Iris fulvas that preceded the evolution of Iris nelsonii in the vicinity of the Vermillion River and then nelsonii retained this trait as it went on to cross with giganticaerulea and brevicaulis and become a super fulva? Or did the trait turn up in the mix that happened as the three species came to interact here? I don't plan to pass up a wild fulva again without looking for a "closed loop."

Randolph was so correct to say "partly enclosed." I am including photos here of individual flowers that have completely closed style arms into a perfect tube. But what I've seen so far is the same plant that produces a perfect tube, on a subsequent bloom produces a one half tube, and can even put out a flower with an open tube. Usually, though, the tube tends to be closed at the back even when the rest ofthe tube (formed by the style arm wrapping over the stamens) remains open.

I first thought, upon seeing this trait, that nelsonii had evolved past its development in 1966, but Randolph's brief inclusion of " stamens partly enclosed by style arm" in his description of Iris nelsonii leads me to believe he saw then an usual trait that still exists in the nelsonii populations living near Abbeville today.

*Steve Shepard is a professional artist living and gardening in Gautier, MS.  He and his wife, Jeanne, grow native and tropical water plants in addition to irises.

* * Randolph, L.F.; "Iris nelson ii, a new Species of Louisiana Iris of Hybrid Origin," Baileva; Volume 14 (1966), pp. 143- 169.