Louisiana Native Iris
1954 publication by Louisiana Cooperative Extension Service
You will be interested in planting Louisiana native irises in your home garden. You can grow them with little difficulty. Once you get started, it will be a fascinating experience because of their color, variety and beauty of flowers.
This popular wild flower ranges from white through all the lavenders, blues and violet to deepest purple. There are also color values of pink, rose, red, bronze and yellow, as well as bi-tones, bi-colors and flecked specimens.
Under best growing conditions in their native habitat, some flower stalks over 6 feet tall have been found and some as low as 4 inches.
The blooming season starts in March on the Gulf Coast and moves northward with the season. The low areas of Louisiana along the edges of its numerous streams have been naturally planted with the wide distribution of the floating native iris seeds.
As garden flowers, wild irises do well under a wide variety of soil and garden conditions and landscapes. They will thrive on highlands and on lowlands. Bog culture is ideal, if the landscape permits. The shallow edge of a lake or pond is a most natural spot for Louisiana irises.
Louisiana native irises have gained national acclaim and are becoming more popular with amateur collectors and gardeners. Nurseries and gardeners are now propagating this rainbow flower for distribution.
Native irises of various types are widely distributed in Louisiana but are more numerous in the Gulf Coast area.
"The Iris Center of the Universe" was the phrase coined by the late Dr. John K. Small, authority on plant life, to describe the rich, wild iris fields of southern Louisiana. Dr. Small, as curator of the New York Botanical Gardens, was one of the first to describe these fields and to call attention to their magnitude, to the great variety of the flowers and to the unusual size of the plants.
The vicinities of New Orleans, Thibodaux, Houma, Morgan City, Prairieville and Abbeville are melting pots of rainbow colors. Here are found the hybrids resulting from natural crosses of two or more of the following three species: giant blue (giganticaerulea), rust-red (fulva), and dwarf blue (foliosa). These hybrids usually occur where many different types of irises have grown for some time close together in one small area.
The Abbeville fields, where the three species are found, are located near a converging point of several streams. Because of the masses of rainbow colors, the area is referred to locally by iris collectors as the "Iris Heaven."
SPECIES AND TYPES OF NATIVE IRISES
In discussing types of native irises, the author proposes to give only a general description of five types found in Louisiana. He makes no attempt at botanical classification. Much research needs to be done by botanists and geneticists on systematic classification of native irises.
The small, numerous blooms of rust-red shades are on erect stems about 30 inches in height. Both petals and sepals droop and have no signal patch. Rust-red occurs in color values of crimson, pink and even clear yellow. It grows abundantly in the lowlands of the Mississippi and Red River valleys, being more numerous and larger near the Gulf Coast. This iris was first described in 1812. It occurs naturally as far north as Missouri and Ohio.
The Abbeville Red or "Super" fulva is found in southwest Louisiana near Abbeville. These giant reds are in a class all their own. The color range is from red to yellow and brown to deep purple. The wide, overlapping petals and sepals are sometimes marked with a long crest or signal patch. Sometimes they are devoid of any signal markings. Most blooms have a wonderful substance and may be of crepe-like texture and a velvety sheen. The style arms are short. The foliage is broader and the rhizomes are larger than those of the regular fulva.
Dwarf (foliosa, including Flexicaulis, Brevipes and Mississipiensis)
The flower is medium-size. It has much substance and a color range from blue to white. Blooms usually occur low in the foliage on zigzag or fairly straight stems. Plants and rhizomes are much smaller than those of other forms. This type blooms later and grows usually in shadier places than others. It is found growing naturally in the prairie and bluff areas of Louisiana. The Dwarf occurs from Vermilion Parish to West Carroll Parish and east of the Mississippi River from Ascension to West Feliciana parishes.
Giant blue (giganticaerulea)
The large, recurving flower parts range in color from blue and purple to white. Flowers with vertical petals (standards) and horizontal sepals (falls) are borne at different levels on tall, erect stalks. These Giant Blues are found along the Gulf Coast of Louisiana on the edges of bays fed by fresh water and bordering on salt water marshes.
Pine Flat Types (virginica, including Versicolor, Shrevei and Carolina)
The medium-size flowers range in color from deep blue to white, with heavily-veined, fragrant blossoms on lateral, branching, slender stems. The dark green foliage has a decided midrib. This characteristic is not found in any other Louisiana native iris. Pine Flat Types are not known to cross-pollinize with other forms of Louisiana native irises. Natural habitats of this type are in the low, pine flat areas of southeast and western Louisiana from Calcasieu to Caddo parishes. East of the Mississippi River they occur abundantly north of lakes Pontchartrain and Marepas. The soils in these areas are more acid than in the alluvial and bluff areas where other Louisiana irises grow naturally.
HORTICULTURAL VARIETIES AND HYBRIDS
Hybrids found in the wild, as well as those produced in the garden by hybridizers, number in the thousands. As these hybrids make good, they may be given a variety name. Some of the best irises have no name, while others have several names. Many of the named hybrids have been registered and the descriptions recorded with the American Iris Society.
The group of plants collectively classed as "Louisiana Irises" is composed of three principal species and their hybrids. The species are I. fulva, the red or flame-colored iris of the Lower Mississippi Valley; I. giganticaerulea, the tall blue of the Lower Gulf Coast; and I. foliosa, the little blue-to-lavender dwarf of the bluff or terrace lands.
Iris virginica is also native to Louisiana but it grows in regions outside of the State and does not hybridize with the other species. It is largely a native of the poorer pine flatlands.
More information on varieties or hybrids can be obtained from the publications listed at the end of this article.
Growers of irises are interested in increasing the quantity of their best varieties. There are two practical methods of perpetuating or increasing iris stock--by the vegetative process and by seed propagation.
Iris plants increased by this method will produce plants identical to the variety from which they were propagated. This is the only sure way of maintaining an established strain of iris without variation of bloom and plant. Propagation by seed may vary greatly from the parent plant, unless it is a pure strain.
Vegetative increase may be obtained by (1) rhizome separation, (2) rhizome cuttings and (3) flower stalk off-shoots. The ideal time of year for success with the first two practices is after the dormant season in later summer and early fall (August to October in Louisiana). The other good time is in early spring at blooming season (March to May in Louisiana).
The advantages of spring propagation are that it is easier to identify plants when in bloom and there is less rotting of the rhizomes. However, planting may be done at any season of the year.
Under natural conditions, single rhizomes usually multiply two- or three-fold in a year but have been known to multiply 21-fold, spreading radially. When a single rhizome forms a bloom stalk, it usually produces also two side shoots. These shoots from new rhizomes and continue the process of natural increase. However, the original rhizome usually deteriorates as increased growth takes place. Similar multiplication will occur naturally under good garden conditions without mechanical separation but the process can be speeded by mans help.
One clone from a two-year-old seedling plant in the writers garden developed radially into 21 side rhizomes. This is unusual. But imagine how much increase could be obtained in several years, if a plant like this could be separated and given more room to develop. Most plants will produce an average of three to six side rhizomes the first year or two. By this method, they can be increased to as many as 15 to 20 plants in one year.
Mechanical separation is easily done by breaking off the side rhizome from the main one and transplanting it immediately. The main rhizome with the bloom stalk is then likely to spout out more shoots from the dormant buds at the leaf scars. The ring-like scars on the rhizomes indicate where the leaves were attached. At each scar there is a bud or potential new plant .
Cuttings of 2- to 3-inch sections of the rhizome should be planted in propagating media, such as vermiculite or well-rotted leaf mold, peat moss and sand or sphagnum. Avoid planting cuttings too deep. Just barely cover and keep them moist in a cool, shady place. Be careful not to over-water or soak, since this may cause them to rot.
As each new shoot reaches 4 to 6 inches in height, carefully remove the rhizome cutting, new shoots and all new roots formed in the growth medium and place them in a bucket of water until planted. With a sharp knife, separate the new plant with all its new roots from the rhizome section. A portion of the rhizome may be sliced off in this process. The new plant should then be transplanted in a well-prepared, fertile plant bed and shaded until well grown out. The rhizome cutting should be replanted in rooting media to develop additional plants. The process can be repeated until all the buds on the cutting have been developed.
Flower Stalk Off-shoots
This method of propagation may supplement the others, if a maximum increase of a desirable, rate variety is wanted. The off-shoots on the stalk are similar to those of the day lily. However, the flower stalk buds at the leaf nodes must be stimulated into growth. Do this by cutting the stalk while it is still green, after blooming, but before the seed pods form. Then place the flower stem in a container of water so that the water line is slightly above the base of the leaf node and keep it in the shade.
Another method is to place the flower stalk almost horizontal in a sand propagating box. When the off-shoot an dits roots have developed, remove the off-shoot from the flower stem and transplant it.
Seed pods will develop on most wild irises. If pollinated, each pod will produce from several to about 60 cork-like seeds. This method of increase is very important to iris hybridizers in developing new forms and colors but is slow. All the seeds in a pod may not germinate the first year.
Gardeners who desire large quantities of plants for mass plantings may be interested in using seeds also, if trueness to variety is not important. Most Louisiana irises are hybrids and their seedlings will vary in color, size and form.
If iris seeds are left on the stalk to mature fully and harden, they germinate very slowly. The fully matured, late harvested, dried-out seeds will go into what is known as a "rest period" and it may take several years for all of them to spout. However, you can hasten germination of iris seed by harvesting them when the seed pod is still partially green. Planting at harvest time (June and July in Louisiana) will produce a higher percentage of seedlings by fall and early spring.
Use of Flats
Do not plant seed in garden beds, because weeds will choke the plants and heavy rains may wash the seeds away. A better plan is to plant in flats, cans or other containers partially filled with a good propagating medium, such as vermiculite or leaf mold and sand.
Good drainage is important. This is best accomplished by making small holes in the base of the cans or other containers used.
Plant seeds approximately ½ inch deep, water thoroughly and place in a cool, shady spot. By all means, protect seed from rats. Keep seed moist until all are sprouted but do not over water, since this will cause the seed to rot. As the seedlings emerge to 5 or 6 inches in height, lift them carefully, avoiding damage to the tender, new roots, and transplant them in a well-prepared, rich soil that is high in organic matter. Space plants about a foot apart in the beds.
The best seasons of the year for transplanting wild irises are fall and spring, although it can be done at any time. During hot weather, wild irises do not grow and are more susceptible to rot when rhizomes are exposed to direct, hot summer sun. Most of their growth occurs during rather cool weather. Getting irises transplanted and established in the garden by late summer or early fall increases chances for a bloom crop the next spring.
In collecting plants in the wild or digging them in the garden, you may use either whole fans (large blooming stalk rhizomes with side shoots) or small single-side rhizomes about 3 to 4 inches long. It is best to do this during the blooming season, because of identification. If identity is to be kept, attach labels at digging time.
If plants are to be shipped a long distance, or held over for some time after digging, you may pack them in moisture-retentive material, such as damp sphagnum or vermiculite. The stored food in the rhizome keeps the rhizome from deteriorating very fast.
Set the plants about a foot apart in the garden. Shallow planting is best, with the top of the rhizome level with the top of the soil. Then mulch the beds with an inches of well-rotted organic matter, such as plant leaves, peat moss, sugar cane bagasse, cotton gin mote, rice hulls or rotted sawdust. Water thoroughly and repeat occasionally, if dry weather prevails. After transplanting the young seedlings, which are small and delicate, give them special care until they become well established.
Creating New Irises
Amateur hybridizers among iris growers are increasing in number by leaps and bounds. They are creating new irises by cross-pollinating and by self-pollinating desirable flower varieties. This is easy to do and the number of possible new varieties is endless. Once you get started, it is just as much fun as walking the swamps to find new natural hybrids. Collecting in the wild as a means of getting new floricultural varieties will require a lot of time and travel. Buying from nurseries may be costly.
When you make crosses and produce seedlings of your own, the pleasure in gardening increases. Waiting for your own seedlings to bloom is like waiting to open a Christmas package. If the bloom and plant are "super" and make good, then the thrill approaches that of parental pride.
Method of Hybridizing
The technique of hybridizing is very simple. A little practice and experience will start you on the way to iris breeding.
Just before the fully-grown flower bud on the mother stalk opens, it should be carefully forced open. This is done by firmly holding the base of the flower with the left hand, lightly pinching the tip of the bud with the right hand and twisting it open. Remove the male parts, or stamens, immediately so as to avoid accidental contamination. A pari of eyebrow tweezers is an ideal instrument for this. At this stage, the stigma (female part) is highly receptive. It is a simple trick then to expose the stigmatic surface by raising the claw and thoroughly dusting the exposed surface with mature pollen which was removed from the desired male plant. To do this, simply rub a well-opened stamen on the stigma and the flower is pollinated.
This completes the operation, except that the flower should be bagged to prevent later contamination by insects or other natural agents. Some hybridizers just break off the sepal instead of bagging the crossed bloom.
The next step is to tag, label and date the cross; example: fulva x foliosa--3/24/49. The female or mother plant is always listed first. In the case of self-pollinating a bloom, use the symbol X; example: Bayou Sunset X--3/24/49.
Typing the stalks to small stakes may keep them from bending to the ground. This will prevent seed pod rot and make the seed less accessible to rats, which relish iris seeds.
Plant breeding, of course, presents a problem of inheritance. All wild irises possess the important hereditary factors of color, size, form, substance of flower, disease resistance and other plant characteristics. However, you do not have to be a professional geneticist to develop outstanding new irises. When you do develop a good hybrid, it can be rapidly propagated vegetatively. It is important to have a healthy, vigorous grower and a well-adapted individual.
Selecting desirable parent stock will, of course, be somewhat of a problem until you have gained experience but you may be lucky, if you try.
SOIL PREPARATION, CULTIVATION
Soil and cultural requirements of the native irises are the opposite of those of the bearded iris. Natives thrive best in slightly acid or sour soil, with abundant moisture. The bearded do their best in alkaline or sweet soil and with very good drainage. Highland, lowland or even bog conditions are satisfactory for the natives.
In locating plant beds in your landscape plan, remember that wild irises require moisture and humus. Most varieties thrive and bloom best in full sun to semi-shade. Some of the foliosa types do well in partial shade. Necessary protection from the hot summer sun should be provided by mulching. Good seedbed preparation prior to planting, then mulching over the rhizome and around the plants immediately after planting will reduce the need for cultivation.
Deep plowing or spading, followed with thorough harrowing or raking, is essential to good soil preparation. Deep preparation improves the physical condition of the soil, increases its ability to absorb and retain moisture, makes the natural and supplementary supplies of plant food more readily available and helps to destroy unsightly, harmful weeds.
Very little cultivating will be needed, except to control weeds. A small, narrow spring-tooth garden tool is ideal for cultivating. If a hoe is used to cultivate in the fall and spring, take care not to cut the shallow rhizome. Under no circumstance, should you use a hoe in the iris bed during midsummer when the shallow dormant rhizomes are so easily disturbed.
Thin plantings of summer, shade-producing legume plants, such as soybeans or crotelaria, may be made after the iris-blooming season. This will protect plants form sun, conserve moisture an control weeds.
Plenty of organic material, such as animal manures, compost or green legume crops turned under with the soil, plus commercial fertilizer, is necessary for a good iris bloom crop. Poultry yard manure is the most effective for irises.
The well-rotted organic material should be worked into the soil while preparing the beds and also spread lightly over the rhizomes just after planting. Use at least a good wheelbarrow load per 6 to 8 square feet.
Supplemental plant food in the form of commercial fertilizer should be used in several applications both in early fall, when roots start developing, and in very early spring, about two months before blooming. A nitrogen fertilizer, such as nitrate of soda, sulphate of ammonia or ammonium nitrate, is recommended for very early fall at the rate of 1 pound per 100 square feet. This should be thinly spread between the plants.
A complete fertilizer (nitrogen, phosphorus and potash) applied in January or February of about two months before the blooming season will increase your chances for good quality and size of blooms. Any complete garden fertilizer available in your local stores should be suitable. However, an 8-8-8, 6-12-6 or 5-10-5 is recommended. Apply this mixture around the plants at the rate of 2 or 3 pounds per 100 square feet.
Water is essential for natural distribution of Louisiana irises, for the establishment of young plants and for a good bloom season.
Moisture is most needed during fall when plants are getting established and in early spring for about two months prior to blooming. This usually coincides with the rainy seasons in Louisiana.
During these periods, if weather is too dry, it may be necessary to irrigate thoroughly. One thorough soaking of the iris beds is better than an occasional, light sprinkling. Soils high in organic matter store more moisture for dry seasons. This is why irises do so well in a fertile soil where a lot of humus and a liberal mulch have been added.
Planting the irises in depressed beds will facilitate irrigation. This is even more important in the drier hill sections of Louisiana. Bog culture, when the landscape plan permits, will help to solve this problem.
DISEASES AND PESTS
Louisiana irises have few pests or enemies. Some of them follow.
Rot or Mustard Seed Fungus
It occurs in the soil and may attack susceptible iris plants at the ground under warm, wet soil conditions. A fungicide, such as Terraclor, applied to the soil as a dust or in a solution may help to reduce the damage. An effective way to control this soil fungus, if it becomes a serious problem, is to move the irises to another location temporarily and treat the soil with Terraclor. When the disease appears, apply the fungicide to the soil at the rate of 4 oz. of Terraclor per 100 square feet. Be sure to thoroughly mix the fungicide with 4 to 6 inches of the top soil and then replant. Remove the dead foliage to admit sunlight to the base of the clumps.
Some of the earlier blooming varieties are susceptible to this disease. You may have to discard the most susceptible varieties. Removal and burning of all the diseased leaves as soon as they appear will help to control rust. A spray of Fermate or of Zineb may also check the disease. Use these fungicides at the rate of 1/4 pound to 10 gallons of water and spray the leaves when the rust spot first appears.
If orioles fly in at iris blooming time, they are likely to go for the nectar in the flowers and tear them up. How to stop them is a problem.
After the blooming season, when irises go into dormancy and the dead leaves are removed, sun scald often does a lot of damage to the exposed rhizomes. This may cause rot. The damage can be easily corrected by covering the rhizomes with mulching material or soil.
Preparation of Native Irises for Exhibition
(1) Three or four days before the show, go over the garden and decide what you will exhibit. (2) Label each bloom stalk. (3) Wrap each bud loosely in wax or cellophane paper and fasten the wrapping securely with a pin or paper clip. This is done to prevent damage by orioles or insects and to prevent breakage in transporting. (4) In late afternoon before the show, cut the stalks 3 inches from the ground. Place the stalks in a container of water but do not let the water cover the buds. Leave in a cool, shady place for at least 12 hours to condition. (5) Remove the stalks from the water and place them in a large, flat cardboard box for transporting to the show. They may be re-soaked, prior to exhibiting, if time permits.
Upon arrival at the show, get entry tags and tie them on the stalks. Place each stalk in the container of water where it is to be shown. Then remove paper covering from buds and allow them to unfurl.
You Will Be Interested in . . .
Arceneaux, George--Breeding Louisiana Iris, Home Gardening, pages 92-93, April, 1947
Dorman, Caroline--The New Irises of Louisiana, The American Home, 11:6, May, 1934
Dorman, Caroline--Those Fabulous Louisiana Irises (special A. I. S. bulletin), November, 1947
Dorman, Caroline--Louisiana Iris Journal--1949, Home Gardening, New Orleans, October, 1949
Dorman, Caroline --Flowers Native to the Deep South, 1958
Nelson, Ira S. --A Review of Louisiana Irises, The National Horticultural Magazine, pages 183-192, October, 1944
Reed, George M. Excerpt from A. I. S. Bulletin No. 106, July, 1947
Small, John K. 1931 Manual of the Southeastern Flora, New York Botanical Garden
Viosca, Percy, Jr. --The Irises of Southeastern Louisiana, April, 1935 (Reprint from A. I. S. bulletin)
Other special articles on Louisiana Irises are to be found in bulletins of the Society for Louisiana Irises, Lafayette, Louisiana, and bulletins of the American Iris Society, Nashville, Tennessee.