By Christy Jones
Louisiana irises have long captivated plant lovers, with their unique, six-sided seed capsules and colorful blooms in stunning shades of red, copper, lemon yellow, and deep blue. Although they now appear in gardens across the South, more than a century ago, collectors and horticulturists braved the swamps, bogs, and bayous of the lower Mississippi River Valley and the Gulf Coast plains to find them. It took many years after their discovery for the showy ornamentals to arrive in stores.
First classified by Thomas Walter in 1788, Louisiana irises (Iris ser. Hexagonae) include five iris species native to Louisiana and surrounding regions of the southeastern United States: Iris hexagona, Iris giganticaerulea, Iris brevicaulis, Iris nelsonii, and Iris fulva.
The plant group was first referenced in the 1820s, when John James Audubon called them “Louisiana flags,” and again a century later, when the Bulletin of the American Iris Society described them as Louisiana irises in its June 1920 publication. Dr. John Kunkel Small popularized Louisiana irises in 1931 after collecting and recording more than 40 wild iris cultivars for his employer, the New York Botanical Garden.
The first commercial Louisiana irises were sold by catalog in 1933 and quickly became popular worldwide because of their showy blooms and prolific nature. Unfortunately, their native habitat has dwindled. Many boggy areas around southern Louisiana were developed for agriculture, industry, and housing, threatening many native iris species.
To ensure the survival of the species, plant collectors and breeders Marie Caillet, Josephine Shanks, and William “Dean” Lee arranged for land to be set aside for new Louisiana beds at Mercer Botanic Gardens during the mid-1980s. The trio sought donations and eventually secured Mercer’s original Louisiana iris collections. Mercer staff members installed the plants around the Lily Pond (now Storey Lake) and in the Hickory Bog, the Ginger Garden (now the Tropical Garden), the Endangered Species Garden pond, and the Forest Floor Garden bog.
Because of the unfortunate, severe damage from the Tax Day flood in 2016 and Hurricane Harvey, many of Mercer’s Louisiana irises were lost. The Hickory Bog still has some Louisiana irises, although signage has been lost. To prepare Storey Lake for construction, The Mercer Society dug up many irises in early 2020 and sold them at March Mart as unknown varieties.
As work around Storey Lake concludes, Louisiana irises are once again returning to Mercer. Thanks to Commissioner R. Jack Cagle, Precinct 4 Parks Director Dennis Johnston, volunteers, and park staff, Mercer’s collection of Louisiana irises has grown to include more than 75 different varieties.
Mercer’s newest Louisiana iris, “Empress Josephine,” named in honor of Josephine Shanks, is a 32-inch stunner featuring ruffled, dark red-violet blooms with bright gold spears.
Carol Price, the daughter of Shanks, recalled visiting Mercer’s Storey Lake and other Louisiana iris gardens in Houston, Lafayette, La., and other cities to learn about the flower.
“My mother was very passionate about Louisiana irises and enjoyed sharing that lifelong passion with others,” she said.
Mercer’s horticultural operations coordinator, Jeff Heilers, curated the new collection, choosing varieties based on height, color, cost, and bloom sequences to provide a longer display.
“We have the greatest selection and the longest blooming season for our budget,” he said. “Visitors can glimpse this display March through May.”
The Mercer Louisiana iris collection showcases multiple shades of blue, lavender, mauve, red, yellow, orange-red, pink, and cream, with varying heights, ranging between 25 and 42 inches.
Most varieties appear in tall flues around Storey Lake, creating a beautiful backdrop of color and inspiration for the public. Other irises appear in large flower beds in boggy areas of the gardens.
“It will be nice to have the Louisiana irises back in the gardens after their removal following the Tax Day and Harvey floods,” said Mercer director Chris Ludwig. “These new additions will more than double the size of the original collection.”