Leaf Strip

The Classifications of Bearded Irises

We will begin with the smallest of the bearded iris, the Miniature Dwarf Bearded or MDB class. To be in this class an iris must consistently produce flower stalks that are no taller than 8 inches. They usually have small and dainty flowers that measure from 4.0 to 7.5 cm (1.6" - 3") wide. MDBs are the first irises to bloom in the spring. They usually show little or no branching.

The Standard Dwarf Bearded or SDB class, consists of iris with bloomstalks that must be between 5 to 10 cm or 8-16" in height. Stems may be branched or unbranched, usually with two or more terminal buds. Blooms should be from 5 to 10 cm (up to, but not including, 4 inches) wide. To determine flower width, measure horizontally from the center of one fall to the center of an adjacent fall. Leaves should be essentially erect and no taller than the height of the bloomstalk. The SDB bloom season begins after the peak of the miniature dwarf bearded iris and before the peak bloom of the intermediate irises. In Maine many of the SDBs bloom mid to late May depending upon the variety while in southern New England, SDB bloom begins in late April or early May.

The Intermediate Bearded or IB class produces bloomstalks that may vary in height from 41 to 70 cm or 16" to 27.5". Shorter than 16", or taller than 27.5" and the iris in question cannot be classified as an intermediate iris. Blooms should be 9 to 13 cm or 3.5 to 5 inches. This measurement is taken by measuring the distance between the tip of one fall to the tip of an adjacent fall. The typical blooming period for the intermediates falls between the bloom times for the SDBs and the tall bearded bloom season. An iris in any class may produce bloomstalks inconsistent with its official classification. Weather and climate, poor or very fertile soil, may cause an iris to produce stalks that are taller or shorter than the height recorded at the time of registration.

Miniature Tall Bearded iris or MTB comprise a separate class of bearded iris, also known as table irises, that produce bloomstalks of 41 to 70 cm (16" to 27.5") in height. However, MTBs are not simply very small flowered tall bearded irises. In all aspects of the plant, MTBs are far daintier. Blooms on MTBs should not be more than 15 cm or 6 inches in combined height and width. They are borne on slender, wiry, flexuous stalks 1/8" to 3/16" wide directly under the terminal flowers and increasing gradually to about 5/8" at the ground line. Although most miniature talls bloom with the tall bearded irises, size and proportion, not the season of bloom, define the class. MTB blooms are very dainty, especially when compared to those of border bearded or tall bearded iris blooms. Their slender stalks and dainty blooms make them ideal subjects for use in arrangements.

Iris in the Border Bearded or BB class must consistently produce bloomstalks of 41 to 70 cm, or 16" to 27.5". This is the same as the stalk height for the intermediate and miniature tall bearded. So what distinguishes this class from the other two? First, border bearded irises should bloom along with the tall beardeds. Second, blooms should be larger than those of the IBs or MTBs, but the width of the flowers should not exceed 5". The height of the flower, measured vertically from the highest point of the standards to the lowest point of the falls, should not exceed 22 cm or 8.5". In other words, flowers in excess of these measurements would likely resemble tall bearded blooms and would look out of place on a plant producing bloomstalks less than 27.5" in height. Border bearded irises should closely resemble the plant and flower habits of tall bearded irises, but should be reduced in size for proper balance.

Iris in the Tall Bearded or TB class produce bloomstalks that are not less than 27.5" in height. Of course the vast majority of tall beardeds produce stalks that greatly exceed this minimum height standard; many varieties produce stalks of at least 38" to 42". Blooms should be considerably larger than those of the border bearded and intermediates bearded irises. And they bloom after most of the IBs have finished blooming.

Who officially assigns bearded irises to a certain class? It is the responsibility of the hybridizer of an iris to be registered to properly assign it to the right class. Once AIS Registrar Keith Keppel receives the application for registration, the plant is officially registered according to the information provided by the hybridzer.

Can the classification of a registered iris be changed if the stalks of an iris grow to greater heights in other gardens where they are grown following their introduction? Changes in classification can be made by the hybridizer of an iris if he makes a formal request to the registrar. However, it should be noted that changing from one class to another is not something that happens very often. This indicates that most all iris hybridizers are doing a good job when registering irises. One of the harder irises to classify is the border bearded iris because in some gardens it may grow taller than 27.5", the upper limit for stalk height. How an iris performs in the hybridizer's seedling plot will usually dictate how the plant will be registered. If a hybridizer wishes to test his seedlings in various climates and gather data for registration proposes, he may do so; however, most hybridizers do not send their seedlings to various test plots prior to introduction. They rely pretty much on how the plant performs in the home garden.

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