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Louisiana irises, Delta Journal, The Times-Picayune, July 22, 2007, C-9

Delta Journal
by Bob Thomas

Spring is the season in south Louisiana to see irises of a variety of colors. Irises are aquatic plants that enjoy lots of sun and wet feet for much of the year. Irises seem to easily hybridize, and some that are now recognized as species are of hybrid origin (e.g., the Abbeville Red Iris, Iris nelsonii, resulting from hybridization of Iris giganticaerulea and I. fulva).

Our native irises are blue or copper colored. If one encounters yellow, purple, white, or multi-colored irises, they are normally hybrid forms that were originally found in the wild around New Orleans and are now widely cultivated. But, I recently saw at the Louisiana Nature Center a cream-yellow flower on an Iris giganticaerulea that otherwise possessed the typical beautiful blue flowers of the species.

The following are our common native species.

Giant-blue (Swamp) Iris - Iris giganicaerulea - This is the tallest and bluest of our native irises. It is fond of swamps, though it will grow almost anywhere. The flowers are at or near the top of the plant, with no or very little length of leaves above them. The plants may grow to 5 or 6 feet tall.

Zig-zag-stemmed Iris - Iris brevicaulis - The stems with flowers appear to zig-zag, i.e., not tall and straight. The flowers are lighter blue than the Giant-blue Iris, and the flowers are below the level of the tallest leaves. The leaves are about 2 feet tall.

Southern-blue Flag - Iris virginica - The leaves are about 2 feet tall, and the light blue flowers that have a large yellow center are 3 feet tall.

Copper Iris - Iris fulva - This species is easily identified since the flowers are a copper color. Though not seen very often, it may be locally abundant.

The Yellow Flag (Iris pseudoacorus) is a yellow flowered Old World species that has become commonly established in many areas in southern Louisiana. It has tall broad leaves that stand 4-5 feet tall, and is easily identified by the presence of an obvious rib running down the center of each leaf. It has a series of dots arranged in a “v” on each petal.

Remember, if the flowers are purple, white, or other non-blue/non-copper colors, the plant is a Louisiana Iris of hybrid origin.