The Classic MDBs

 by  Tom Waters

The world of dwarf and median irises was revolutionized in the 1950s when Paul Cook and Geddes Douglas crossed the dwarf species Iris pumila with tall bearded irises (TBs) to create what became known as standard dwarf bearded irises (SDBs). The new SDBs were not only lovely, varied, and useful garden plants in their own right; but they were fertile parents, leading to all sorts of new avenues for hybridizers.

Hybridizers soon tried crossing the SDBs back to both of the parent types, TBs and I. pumila. Crossing SDBs with TBs produced a whole new style of intermediate bearded irises (IBs), whereas crossing SDBs with I. pumila produced a new style of miniature dwarf bearded irises (MDBs).

'Bee Wings'
photo: El Hutchison

By ancestry, these new MDBs were 1/4 TB and 3/4 I. pumila. From I. pumila, they inherit daintiness, earliness of bloom, and floriferousness. The TB ancestry lends them a greater variety of color and pattern, and a bit more width and polish in flower form. Dwarf breeders and growers were delighted with these creations; and they became quickly popular, all but replacing the earlier dwarfs from I. lutescens breeding in just a decade or so.

'Alpine Lake'
photo: Tom Waters

The first MDB from SDB x I. pumila breeding to win the Caparne-Welch award was Alta Brown's 'Bee Wings' (Brown, 1959), which won the award in 1963.  By 1990, six others from this type of cross won the award. Especially notable among them were 'Zipper' (Sindt, 1978), a deep yellow with a stunning blue-violet beard, and 'Alpine Lake' (Willott, 1980), a soft near-white with a diffuse blue spot. I refer to these as "classic" MDBs, because they set the standard for the class during this time of great progress and interest.

'Zipper'
photo: Jeanette Graham

Another popular type of MDB was produced by crossing SDBs with each other and selecting irises that were small enough to fall under the height limit of the MDB class (currently 8 inches). These had the advantage of showing all the color patterns of TBs, including plicata and tangerine pink. Although both types were popular, hybridizers breeding specifically for MDBs preferred the SDB x I. pumila cross, which produced a much greater proportion of early-blooming, MDB-sized seedlings.

After 1990, the SDB x I. pumila cross gradually fell out of fashion, with most of the new MDBs coming from SDB x SDB breeding. The reason for this is two-fold. First, the SDBs had been steadily progressing in color, pattern, and form; and the classic MDBs from SDB x I. pumila could not really keep up. Second, fewer breeders were breeding specifically for MDBs and growing I. pumila for that purpose. Most breeders were instead working with their established SDB lines, which sometimes produce MDB-sized plants "by accident," as it were. So the SDB x SDB cross would do double duty, producing both SDBs and MDBs.

'Wee Dragons'
photo: Jeanette Graham

Classic MDBs are still being produced, however. My favorite recent one is Lynda Miller's 'Wee Dragons' (Miller, 2017). The recent Caparne-Welch winner 'Kayla's Song' (D. Spoon, 2008) is of complicated ancestry, but its overall appearance makes it likely that it too is 3/4 I. pumila and belongs in this category.

Although it is clear that the MDBs from SDB x SDB breeding will continue to dominate the class with their modern form and exciting color patterns, the classics should not be completely forgotten. The advantages of early bloom and guaranteed dainty size in all gardens should not be set aside too quickly. And since this type of cross is not often made these days, we don't have a very full picture of its potential when modern SDBs are involved.

'Kayla's Song'
photo: Ginny Spoon

Although my own hybridizing interests are focused elsewhere, I make some SDB x I. pumila crosses each year and donate the seeds to the Dwarf Iris Society seed sale, in the hopes of encouraging interest in the classic MDB cross.

If you grow MDBs, keep your eye out for classic MDBs that have I. pumila or one of its cultivars as a parent. They will delight you with their early bloom and daintier looks.