Monday, September 5, 2016

The Louisiana Iris Species Preservation Project

By Patrick O'Connor

In 2015, the Society for Louisiana Irises adopted a proposal by Charles Perilloux of Baton Rouge to create a “Louisiana Iris Species Preservation Project.”  At the 2016 SLI convention, procedures and plans for the project were approved, and work has begun.

The problem that has precipitated the need for the project is the disappearance from the wild of many of the forms of the five generally recognized Louisiana iris species which comprise the Series Hexagonae:  I. hexagona, I. brevicaulis, I. fulva, I. giganticaerulea, and I. nelsonii.  When the modern “discovery” and introduction to these plants to horticulture occurred in the 1920s and 1930s, they were already recognized as endangered.  Dr. John K. Small first encountered these irises in Louisiana in 1925, and his subsequent publications in the Addisonia: Journal of the New York Botanical Garden were entitled “Vanishing Iris” and “Salvaging the Native American Irises” (both 1931).

I. fulva 'Ouachita Half Moon' (Thomas Barham)
I. fulva 'Shangri-la Pass" (Benny Trahan)
I. fulva dwarf from Illinois
In Louisiana the irises are not currently threatened everywhere.  One can still see large stands of native irises in freshwater swamps and low wild areas.  But the extent of these natural spaces has diminished markedly over the years.  The current city limits of New Orleans, for example, once contained massive fields of irises, but development has destroyed them all.  Louisianas are often seen in roadside ditches, but one pass of a road grader or a crew spraying herbicide wipes them out.  I. hexagona, the first to be given species designation based on specimens from South Carolina, apparently is entirely gone from its state of origin.

I.. brevicaulis from Gary Babin in Baton Rouge
I. brevicaulis from Point Coupee Parish, LA
It is not just numbers of plants that are threatened.  When a population is destroyed, any unique forms that may have developed in the area are also eliminated.  The Louisiana Iris Species Preservation Project is focused precisely on the need to preserve the range of colors and forms found among the native Louisiana irises. 
And the variety is remarkable.  The species fulva and brevicaulis probably are more varied than the others, no doubt due to a much wider geographic range.  Both extend well into the North, whereas hexagona and giganticaerulea are limited to the Southeast and Gulf Coast states.  I. nelsonii is restricted to a few square miles in South Louisiana near the town of Abbeville.

I. nelsonii 'Bronco Road' (Benny Trahan)
I. nelsonii 'Young's Coulee (Benny Trahan)
It is instructive to see the ranges of these irises displayed on county level maps.  The website of the Biota of North America Program presents beautiful distribution maps of all the irises species native to North America.  Take a look at:  http://bonap.net/NAPA/TaxonMaps/Genus/County/Iris 

I. hexagona from South Carolina

I. hexagona from Florida (Benny Trahan)
Interestingly, the BONAP site recognizes a sixth Louisiana iris species:  I. savannarum.  Savannarum was one of the species names applied by Dr. Small, but most authorities have abandoned it, lumping these irises, found mainly in Florida, with I. hexagona.  BONAP, by contrast, shows hexagona as having a more restricted range from North Florida and up the coast to South Carolina.  I. savannarum, following Small, is an iris that extends from North Florida down to nearly the Everglades.
Saving the variety of species forms for posterity requires a long term and systematic effort.  It will have to be implemented in phases and will take several years to achieve the full scope envisioned.  In years past, many specimens have been “rescued” by those attracted to their unique beauty, but “saved” plants sometimes are forgotten and effectively lost as people pass from the scene or interests change.   Without intervention, much of the genetic diversity of Louisiana irises will be lost to future generations.

I. giganticaerulea 'Barbara Elaine Taylor' (James Taylor)
I. giganticaerulea from LaPlace, LA
The approach of the Louisiana Iris Species Preservation Project is to create permanent collections of representative examples of the colors and forms of each species from throughout its geographic range.  Once established and thriving in the collections, plants would be made available to individuals and organizations consistent with guidelines adopted for the project.

A beginning has been made.  Charles Perilloux chairs the SLI committee overseeing the project.  A list of over 50 specimens, often named irises, has been compiled, and many have been assembled in a planting in New Orleans.  The Greater New Orleans Iris Society is taking a lead role in maintaining an initial core collection using space made available by City Park in New Orleans. “Stewards” have been identified who eventually will maintain duplicate plantings of some or all the irises on the Preservation List. 

The Project is in need of Stewards outside Louisiana.  It is important to identify and maintain forms from the full range of the Series Hexagonae.  At present, some species forms from around the country have been obtained, but all the Stewards reside in Louisiana.  Some of the species, such as some hexagonas (or savannarums) do not thrive in Louisiana growing conditions, and a special effort is needed to create plantings in other states and regions.

The Greater New Orleans Iris Society website has a page on the Species Preservation Project that outlines the organization and procedures of the effort.  http://www.louisianairisgnois.com/SpeciesPreservation/  An upcoming article in the SLI publication Fleur de Lis addresses this also.


The GNOIS website also displays in one place pictures of many of the irises currently included on the Project’s Preservation List.  One often hears about the progress made over the years in hybridizing Louisiana irises and about the color breaks that have been achieved.  A glance at the assembled pictures of the many species forms is an eye opener.  Many of the color breaks we have welcomed were initially supplied by Mother Nature.  As wildflowers, the Louisiana irises were already a remarkably varied group of plants, and the native forms need to be preserved.

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