Spring, especially April, 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 Iris, Iris nelsonii, resulting from hybridization of Iris giganicaerulea and I. fulva)
Our native irises are blue or copper colored. If one encounters yellow, purple, white, or multi-colored irises, they are probably horticultural species that have escaped or some other type of hybrid.
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 be 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 very abundant.
There is a very commonly seen hybrid iris that has a yellow flower and tall broad leaves that stand 4-5 feet tall. Additionally, there is an obvious rib that runs down the center of each leaf. There is a yellow leafed Old World species that has become established in many areas that is called Yellow Flag (Iris pseudoacorus). It has a series of dots arranged in a “v” on each petal.