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. 

Hybridizing with Iris reichenbachii

by Tom Waters

Four years ago, I wrote a blog post here titled “The Untapped Potential of Iris reichenbachii”. At that time, I could comment on the use of I. reichenbachii in median breeding only as a promising theoretical possibility. Now, however, I have some solid results from my own hybridizing work to share.

As mentioned in the earlier post, I. reichenbachii exists in both diploid and tetraploid forms. The diploid forms can be used with diploid MTBs, while the tetraploid forms are compatible with TBs, BBs, and tetraploid MTBs. It was the tetraploid grouping that I was interested in, so my first priority was to acquire tetraploid forms of I. reichenbachii. Alas, none of the plants or seeds available commercially or through seed exchanges have been identified as either diploid or tetraploid, so I had to make this determination myself. Not being equipped to make chromosome counts, this meant making test crosses and patiently waiting for the results.

Happily, it turns out that the tetraploid forms are not uncommon. The first two reichenbachii forms I started crossing with both turned out to be tetraploid. One is a yellow form, a collection from Mt. Vikos in Greece. The second is actually a group of plants of unknown origin I raised from seed obtained from a collector in Czechia. Most of these are violet.

I. reichenbachii ex Mt. Vikos, Greece

Waters T009-02, purple tetraploid I. reichenbachii

Waters T051-01,
I. aphylla X I. reichenbachii ex Mt. Vikos

I have three fertile tetraploid seedlings now. The yellow Mt. Vikos form gave me seedlings with I. aphylla and with the tetraploid median plicata ‘Saucy’ (Craig, 1998, IB). One of the violet forms gave me a seedling with the tetraploid median ‘Night Mood’ (L. Markham, 2003, SPEC-X). All three of the seedlings fall in the SDB height range and have the slender stems of I. reichenbachii. None are any competition for the modern, ruffled, dramatically colored median hybrids being produced these days; rather, their value is in further breeding. Because these plants are so small and dainty, they can be used to add these qualities to tetraploid MTB or BB breeding programs. So the next step is to cross these seedlings with the best modern BBs and tetraploid MTBs. It would be nice to have all the color patterns, form, and substance the modern BBs have to offer, but in a line of plants that was consistently small and delicate. This project is already well underway, as I have hundreds of seeds from using these seedlings over the past two years.

Waters T059-02,
Saucy X I. reichenbachii ex Mt. Vikos

Waters T060-01,
Night Mood X T009-02

A second project using I. reichenbachii is directed toward producing dainty MDBs. Most modern MDBs are produced by accident - they are just seedlings from SDB crosses that fall below the 8-inch height limit. These MDBs can be very lovely in terms of flower form and color pattern, but they can easily grow out of class, and often lack the daintiness and early bloom that one hopes for in a true miniature dwarf.

SDBs are the result of crossing TBs with the dwarf species I. pumila. What if one used I. reichenbachii instead of TBs? The result should plants fully fertile with SDBs and modern MDBs, but much smaller. I have three seedlings so far (more on the way) from crossing the Mt. Vikos reichenbachii with the I. pumila cultivar ‘Royal Wonder’ (Coleman, 2013, MDB). One is purple, the other two are yellow. All our about 5 inches tall, with one or two terminal buds. They bloom earlier, overlapping the pumilas and the first MDBs. They are indeed fertile with SDBs and with MDBs from SDB breeding. Once again, the value of these seedlings is not in competing with the showiest modern hybrids, but in further breeding, where they can be expected to produce a line of consistently dainty and early-blooming MDBs. Again, this project is on its way forward, with many seeds from using these seedlings with modern MDBs and SDBs.

Waters S026-01,
I. reichenbachii ex Mt. Vikos X Royal Wonder

Waters S026-02,
I. reichenbachii ex Mt. Vikos X Royal Wonder

These projects using I. reichenbachii are not for the impatient; they are multi-generation endeavors. Yet, there is something uniquely satisfying in breaking new ground.

Irises in Containers

by Tom Waters

Irises are not usually thought of as container plants, but they can grow quite well that way, and there are a number of advantages to doing so.

Two Iris pumila cultivars,
'Wild Whispers' (Coleman, 2012) and
'Royal Wonder' (Coleman, 2013),
growing happily in a large container

The irises I choose to grow in containers are mostly dwarf bearded irises and the smaller arils and arilbreds. Tall bearded irises look out of place in even the largest containers, and a light container soil mix may not give them the support they need when top-heavy with bloom. The smaller irises, however, are naturals for container culture. They bring the plants closer to eye level for viewing, and allow them to be moved from place to place for best effect. If attractive containers, like oak barrels or terracotta pots are used, the effect can be quite lovely and dramatic.

There are additional advantages to container culture. I tend to put rare or choice plants into containers when I first acquire them, as it makes them much easier to weed and care for. A small iris that might get lost in an overgrown summer garden and succumb to neglect, is kept safe in a container where it can get the attention it needs.

Two forms of the exotic oncocyclus species Iris paradoxa
in a large container with a gritty soil mix

Arils are another good candidate for container culture in climates where summers are too wet to grow them successfully in the ground. The container can be stored in a warm dry place through the irises' summer dormancy period. It is also possible to provide a coarse, well-draining soil mix that would be difficult to maintain in the open garden.

As a hybridizer working with dwarfs and other small irises, I also appreciate that containers make the blooms more accessible. It's much nicer to pull a chair up to a container than to crawl around on the ground to harvest pollen or make a cross.

Most of my containers are inexpensive plastic models, in the largest size possible (two to three feet in height and diameter). Even the smallest irises enjoy a wide and deep root run. I fill them with various soil mixes, depending on what I have at hand, but I usually use a mix of my garden soil (a somewhat sandy silt) and commercial potting soil, sometimes with addition of compost, coarse sand, or even small gravel. The irises do not seem too picky about the exact composition of the potting mix. I like to use a top dressing of gravel as a mulch. It also looks nice, especially if a few rocks are positioned on top to make a miniature landscape.

Even in a container with enriched soil, irises will not go forever without dividing them and refreshing the soil mix every few years. Keep an eye out for overcrowding or declining vigor. Also, it is important to keep to a regular watering schedule; how frequently you water will depend on your climate, but the only time I have lost an otherwise healthy plant in a container was when I accidentally let it get bone-dry in the summer. Containers are less forgiving in this way than garden soil.

If you've never grown irises in containers, give it a try this year! You may find it offers both esthetic and practical rewards.

Iris reichenbachii blooming profusely in a container

What is a Dwarf Bearded Iris?

…and why are dwarf lovers so persistent?

 Tom Waters

'Icon' (Keppel, 2008)

In the beginning, there were no class definitions. The meaning of the term “dwarf bearded iris” was taken for granted, as all the ones being grown in gardens were similar in appearance and distinct from their taller relatives.  If you were botanically inclined, you could turn to a reference like W. R. Dykes’s The Genus Iris to get a list of dwarf bearded species, and safely assume that your garden dwarfs were hybrids or forms of those species.

The 1939 AIS Checklist attempted to be somewhat more helpful by giving a height range in addition to the list of species, setting the boundary between dwarfs and intermediates (which were stated to be hybrids between dwarf and tall bearded irises) at 17 inches. This doesn’t make sense, though, if it is taken as a definition, rather than just helpful descriptive information. What if two of those dwarfs species were crossed and produced a hybrid over the limit? Or what if a dwarf and tall were crossed and produced a hybrid under the limit? Giving both a definition in terms of ancestral species and a definition in terms of height is inviting contradiction unless it is clear whether ancestry trumps height or vice versa.

Perhaps in recognition of this, the AIS adopted a new classification in 1947, based decisively on ancestry. A hybrid involving only dwarf species would always be a dwarf; a hybrid involving only tall species would always be a tall. A hybrid involving both dwarfs and talls would usually be intermediate, but might be deemed either dwarf or tall if that was the group it most resembled. Although this last provision was strangely vague, the definition at least allowed hybridizers to cross dwarfs amongst themselves and register the progeny as dwarfs, without worry about a height limit or other factors.

This classification system was introduced at the same time as Walter Welch was organizing the Dwarf Iris Society (then called the Dwarf Iris Club) and stirring up interest in dwarf hybridizing, so there may have been some impetus to clarify definitions for this reason. Although dwarfs had been widely grown in both Europe and North America for as long as tall beardeds, they had not historically received a great deal of attention. Gardeners took them for granted, and although new hybrids were introduced from time to time, there were no hybridizers who focused on them exclusively or had planned breeding programs solely to produce new dwarfs. Welch turned that around, first by organizing a program of round robins, whereby enthusiasts (many of them recruited from gardening clubs and publications, not just iris societies) could discuss dwarf irises by mail, and then by creating the Dwarf Iris Club in 1950. I believe this was the first specialist iris society devoted to a particular type of iris. With the blessing of the AIS, the Dwarf Iris Club even trained and appointed its own judges, just for judging dwarfs!

In 1951, something happened that put the class definition under unprecedented strain. Paul Cook (a friend and correspondent of Walter Welch) introduced the first three irises of the type we now know as standard dwarf bearded (SDBs), from crossing the tiny dwarf species Iris pumila with tall beardeds. As a dwarf x tall cross, a strong case could be made that these new irises were intermediates, and indeed that is how they were registered at the time. But they were no taller than many of the dwarfs being grown at the time, so this might seem a little inconsistent. Welch and the DIS focused attention on the presence of a small branch in most SDBs, asserting that a branch was disqualifying for being considered a dwarf. Oddly, the list of dwarf species that AIS had been printing and reprinting for many years included amongst the dwarfs Iris aphylla, which is copiously branched.

The 1954 classification made
the dwarf people grumpy

Recognizing that the future might hold even more examples of such “problem children” from newfangled hybridizing experiments, the AIS suddenly reversed itself in 1954, offering a classification based entirely on height, with ancestry deemed irrelevant. This makes sense in a world where parentages have become complex or uncertain. Height is something that can be established with a ruler. Now the boundary between dwarfs and intermediates was set at a rigid 15 inches, regardless of what species the plants had come from or what characteristics they had. Welch and the DIS refused to accept this definition, appalled at the thought of 15-inch branched “intermediates” masquerading as dwarfs! Welch could be an opinionated and difficult person under the best of circumstances, and now he and his supporters had a righteous cause for contention. This caused a rift between the AIS and the DIS whose repercussions are still playing out today. From 1955 until 1973, the DIS had its own awards system, issuing the Welch Award in competition with AIS’s Caparne Award, despite the fact that it tended to be the same irises winning both awards.

Other classification issues were percolating at this time as well. There were movements afoot to recognize the so-called “table irises” and “border irises” as separate from both TBs and IBs. A committee was put together to study all these issues and propose a solution. In 1958, the AIS adopted a classification that has remained in place (with minor modifications) to this day. The dwarfs were separated by height into miniature dwarfs and standard dwarfs, with the dividing line being 10 inches. The border bearded class was created for short TBs, and the miniature tall bearded class was created for the table irises. The DIS had no interest in any of these new classes, not even the SDBs, and so the Median Iris Society was formed with the mission of promoting the five new classes between MDB and TB. A peculiar quirk of this development is that standard dwarfs are considered medians, not dwarfs, in apparent contradiction with their name.

'Alpine Lake' (Willott, 1980)
a classic MDB from SDB x pumila breeding

The 1960s and 1970s were perhaps the most exciting time in the history of dwarf iris development. Although the SDBs themselves were deemed too large to be considered true dwarfs, they had an enormous impact on breeding. Dwarf enthusiasts crossed the SDBs back to I. pumila, producing many charming hybrids, earlier blooming than the SDBs and quite distinctive in appearance, with ¾ of their genes coming from the dainty I. pumila. This became the standard cross to produce MDBs. The class was rounded out by selections of pure pumila ancestry, as well as hybrids from pure SDB breeding that happened to be small enough to fit the definition of the MDB class. These “runt SDBs” did not always meet with the approval of the dwarf purists, although there are a number of fine irises in this category. Indeed, in recent decades these MDBs from pure SDB breeding have come to quite dominate the class, in terms of sheer numbers as well as awards.

'Little Drummer Boy' (Willott, 1997),
an MDB from pure pumila breeding

In light of this history, one can understand why the DIS has remained rather protective of the little irises under its charge, and reluctant to muddle the boundary between the dwarf MDBs and the median SDBs; the dividing line between the classes was reduced to 8 inches in 1976, in part to protect the MDB class from SDB interlopers. It also explains the misgivings of many DIS members about merging with MIS, which has been suggested on a number of occasions. Any of the median classes might seem to have more cause to have its own society, given that they all have more new irises introduced each year than does the MDB class. Yet our history has set us apart, and perhaps it is the very fragility of the class in the face of the much larger (in numbers as well as stature!) median classes that inspires a certain connoisseur’s devotion amongst us.

'Pearly Whites' (Black, 2014),
an MDB from pure SDB breeding

In 2018, the DIS seemed on the brink of demise, with the president and vice president resigning, and the officers voting to merge with MIS. Rather miraculously, this was reversed in 2019, with a grass-roots rallying of the troops under the enthusiastic leadership of Charlie Carver, historic iris conservation advocate and devotee of MDBs. We now once again have a functioning society with a full slate of officers and a content-rich newsletter in final preparation for publication early this year. If you love dwarf irises and would like to be part of this renaissance, the DIS would love to hear from you!

Iris lutescens: The Dwarfs that Time Forgot

by Tom Waters

Dwarf bearded irises may be found growing wild throughout much of southwestern Europe, from Spain and Portugal, through southern France, and into northern and central Italy. Through the centuries, different botanists have encountered them in different localities and assigned different names to them: Iris chamaeiris, I. italica, I. olbiensis, I. lutescens, I. virescens, I. subbiflora, I. bicapitata.

Iris lutescens, raised from seed

By the twentieth century, it was clear that most, if not all, of these were really irises of the same species. Gardeners were most familiar with those from southern France, going by the name of I. chamaeiris, so began referring to the whole species as the “chamaeiris complex”. But the rules of botanical nomenclature require that synonyms be resolved by using the earliest published name for the species. In this case, that honor goes to I. lutescens, the name used by Lamarck in 1789. This is now the correct name for all these irises, with the exception of two irises at the extremities of the species’ range,  I. subbiflora in Portugal and I. bicapitata in the Gargano peninsula of eastern Italy, which are regarded by many (though not all) botanists as distinct species in their own right. Even if these are not regarded as belonging to I. lutescens, they are indisputably very close relatives.

I. lutescens is a delightfully varied species. The flowers are most often yellow, cream, or violet, but there are near-white forms, purples, blends, and bitones. In height, they range from about 6 to 12 inches (15 to 30 cm). The stem is unbranched, with one or two terminal flowers.

Iris lutescens 'Bride' (Caparne, 1901)

Until the second half of the twentieth century, I. lutescens  and a handful of its accidental hybrids with other species were the only dwarf bearded irises known to gardeners in western Europe and North America. Named cultivars were produced by the firm of Goos and Koenemann in Germany, by W. J. Caparne in England, and later by Hans and Jacob Sass, among others, in the US. At this time, the modern dwarf and median classes did not exist, so there was no distinction between miniature dwarfs and standard dwarfs; they were all simply “dwarf bearded”, and spanned the whole natural height range of the species, which straddles both of the modern categories.

Iris lutescens 'Path of Gold' (Hodson, 1941)

Although many people grew a few dwarfs, appreciating their charm and early bloom, almost all the attention of iris enthusiasts in the first half of the twentieth century was focused on the tall bearded. The dwarfs were rather taken for granted, by both gardeners and hybridizers. That began to change with the formation of the Dwarf Iris Society under the leadership of Walter Welch in the 1940s. Welch and his friends were determined to learn all they could to advance dwarf hybridizing, and their interest went beyond the I. lutescens cultivars to investigate other dwarf species, such as I. pumila from eastern Europe.

I. pumila is a diminutive species, about half the height of I. lutescens, single-flowered and almost stemless. Robert Schreiner had imported some seeds in the 1930s, and the species gradually became available to the new dwarf hybridizing enthusiasts. The turning point came in 1951, when Paul Cook in Indiana, who had exchanged his pumila pollen for TB pollen from his friend Geddes Douglas in Tennessee, introduced the first pumila/TB hybrids: ‘Baria’, ‘Green Spot’, and ‘Fairy Flax’. Although technically “intermediates” (as the word was used then, it meant a hybrid between dwarf and tall bearded irises), these new irises were no larger than many I. lutescens dwarfs, even though they often had a branch and a total of three buds! This launched a vigorous debate about classification, which led ultimately to the formation of the Median Iris Society and the four median classes we have today. The SDB class was created to accommodate the new pumila/TB hybrids and the taller I. lutescens cultivars, with the MDB class left for the “true dwarfs”, with a maximum height limit of 10 inches, later adjusted to 8 inches.

From the 1960s on, the SDBs from pumila/TB breeding totally dominated the world of dwarf irises. These SDBs carry an extraordinary genetic legacy (dramatic spot patterns from I. pumila, pinks and plicatas from TBs, not to mention more modern form). There was no interest any more in producing more of the overly familiar yellow or violet I. lutescens cultivars. Even the MDB class was taken over by the new SDBs. Most MDBs from the 1960s onward were produced by crossing the new SDBs back to I. pumila, or (especially in recent decades), just selecting irises from SDB breeding that happen to be under the height limit.

I. lutescens, once the very archetype of the dwarf bearded irises in gardens, is now a curiosity known only to species enthusiasts.

Is there any hope for a lutescens renaissance? At first blush, it would seem unlikely. The modern SDBs have been so developed by decades of dedicated hybridizing that they would seem to have nothing to gain (and much to lose, in terms of present-day expectations of the class) by the injection of I. lutescens into hybridizing lines.

If I. lutescens is to be heard from again in dwarf hybridizing, the opportunity may be in the MDB class. Some MDB enthusiasts have been grumbling of late that the class has been taken over by short SDBs, and is losing something of its distinctive charm. There may be some niche here for MDBs with more of a “wildflower” look, breaking away from the stiffness, width, and ruffling that comes from pure SDB breeding. Just as the MTB class has given a home to the simpler, more modest look of the diploids, perhaps there is an opening for more “retro” MDBs. I. lutescens is fully fertile with SDBs and their MDB progeny, and might add a breath of fresh air to a class that is starting to feel overworked.

Everything old is new again?

Iris lutescens campbelli

The World of Irises is the official blog of The American Iris Society. Now in its 99^th year, The American Iris Society exists to promote all types of irises. If you wish to comment on a post, you can do so at the end of the page and the author or the editors will reply. If you wish to learn more about The American Iris Society, follow the link.

Dwarfs for Every Garden

by Tom Waters

The dwarf bearded irises (those classified as miniature dwarf bearded, or MDB) are a charming addition to any garden. With blooms held eight inches (20 cm) or less from the ground, they are the daintiest of all the bearded irises. They are also the earliest to bloom. In my garden, the first ones open a full two months before tall bearded season.

Almost all MDBs grown today fall into one of three categories. All three groups owe their existence to the eastern European species Iris pumila, which came to be used by American hybridizers in the 1940s.

'Liitle Drummer Boy'

The first category is Iris pumila itself. This tiny species is seldom more than 4 or 5 inches (10-12 cm) in height, with just one bloom per stem. (Actually, the stem is often almost nonexistent, most of the height being in the perianth tube formed by the flower parts themselves.) It comes in a range of colors from white and yellow to blue, violet, and purple, usually with a darker colored spot on the falls. There are a number of cultivars produced by hybridizers or selected from wild forms for their garden value. Some of my favorites are 'Little Drummer Boy' (Willott, 1997), 'Hobbit' (Miller, 2004), and 'Royal Wonder' (Coleman, 2013).

'Hobbit'

'Royal Wonder'

The next two categories came about as a consequence of the creation of the first standard dwarf bearded (SDB) irises in the 1950s. As I discussed in an earlier blog post, the SDBs were the result of crossing Iris pumila with tall bearded irises (TBs). The SDBs averaged about 12 inches (30 cm) in height and would typically have 2 or 3 buds. They are regarded as medians, not as true dwarfs, because of their larger size and occasional branch, something not seen in traditional dwarf irises.

'Alpine Lake'

Shortly after the SDBs appeared, hybridizers crossed them back to Iris pumila to produce irises of truly dwarf stature, but with a little something extra from their TB ancestry: plicata pattern, for example, or wider petals and more flaring form. These were the most common type of MDB in the 1960s, '70s, and '80s. 'Knick-Knack' (Greenlee, 1961), 'Zipper' (Sindt, 1979), and 'Alpine Lake' (Willott, 1981) are good examples of this type.

The third category came about from SDB breeding in an even more direct way. Sometimes crossing two SDBs produces an iris smaller than average. These small ones, if they are 8 inches or less in height, belong in the MDB class, since the definition for that class is based on height, not ancestry. Because so much work has been done to improve the SDB class over many decades, these are often the most "developed" dwarfs in terms of form and variety of color and pattern. Popular examples of this type are 'Dollop of Cream' (Black, 2006), 'Icon' (Keppel, 2008), and 'Beetlejuice' (Black, 2013).

'Dollop of Cream'

'Icon'

Generally speaking, the greater the amount of Iris pumila in a dwarf's makeup, the smaller, earlier, and more adapted to cold winters it will be. Those with less Iris pumila will have larger flowers with greater width and ruffling, a greater range of color patterns, and perform better in warm-winter areas.

There are no official designations for these categories, although hybridizers sometimes identify them by the number of chromosomes: Iris pumila has 32, the SDBs and their small MDB progeny have 40, and the SDB x pumila hybrids have 36.

How can you tell which of these categories and MDB belongs to? Alas, the only way to be sure is to look at the parentage on the Iris Encyclopedia or other resource. In most cases, this will lead you back either to SDBs or to Iris pumila, or else the parentage will be an SDB x pumila cross. If this sort of research interests you, my list of pure Iris pumila cultivars may help make sense of things.

I love dwarfs in all their variety, and happily live in a locale where all kinds grow well. Do you grow dwarfs in your own garden? Which kinds are your favorite?

The Untapped Potential of Iris reichenbachii

by Tom Waters

Today's post is all about an underappreciated bearded iris species, Iris reichenbachii. The name, it seems, is bigger than the iris itself. I. reichenbachii is a dwarf, ranging in height from 10 to 30 cm (4 to 12 inches), with one or sometimes two buds at the top of the stalk. (Very rarely, a third bud may appear further down the stalk.) The flowers are yellow (often with brownish markings or blending), smoky violet, or occasionally clear deep violet.

Iris reichenbachii

The species is native to the Balkan peninsula, from Rumania and Bulgaria through Serbia and into Greece. A related species, I. suaveolens, is similar but smaller. Two other species names, I. balkana and I. bosniaca, are now regarded as synonyms of I. reichenbachii.

As a garden subject, I. reichenbachii is pleasant enough, if somewhat unremarkable. It has found a home with rock gardeners and plant collectors. For those who fancy modern hybrid dwarf and median irises, this little species can seem drab by comparison. The petals are rather narrow, substance is lacking, and the colors can seem a bit murky.

To the hybridizer, however, I. reichenbachii has something unique to offer. Its chromosomes are very similar to those of tall bearded irises, and it is quite compatible with them. Furthermore, I. reichenbachii exists in both diploid (two sets of chromosomes) and tetraploid (four sets) forms. Since modern TBs and BBs are tetraploid, they can cross with tetraploid I. reichenbachii and produce fertile offspring. (For an explanation of diploids and tetraploids, see my earlier blog post Tetraploid Arils, Anyone?)

'Progenitor' (Cook, 1951)
 from I. reichenbachii X TB 'Shining Waters'

In the 1940s, the talented hybridizer Paul Cook did precisely that. A seedling from the cross, aptly named 'Progenitor', was registered in 1951. It was an unimpressive iris of intermediate size, but Cook could see its potential. 'Progenitor' was a bicolor, with violet falls and pure white standards. At the time, this was a new color pattern. (Earlier bicolors were actually variations on a "spot pattern" from I. variegata, and seldom showed the completely solid falls and pristine standards of 'Progenitor'. It is interesting to note that I. reichenbachii itself is not a bicolor. The bicolor pattern resulted from combining its genes with those of the TB parent. By crossing 'Progenitor' back to high-quality TBs, Cook was eventually able to transfer the bicolor pattern onto irises that otherwise showed no resemblance to the modest little dwarf that had given rise to the new pattern. 'Whole Cloth' (Cook, 1958), four generations on from 'Progenitor', won the Dykes Medal in 1962.

Virtually all TB and BB bicolors today (standards white, yellow, or pink; falls blue, violet, purple, reddish, or brown) are descendants of 'Progenitor', and hence of I. reichenbachii.

But there is still more to be done with this interesting little species. When Cook was making his crosses, there was very little interest in dwarf or median irises. In fact, medians as we know them today hardly existed at that time. So Cook simply worked to transfer the new color pattern into TBs. Today, however, there is considerable interest in breeding medians, especially BBs and MTBs that are consistently small and dainty. Surely the little dwarf I. reichenbachii has something to offer in these endeavors. The tetraploid forms are compatible with BBs and tetraploid MTBs, while the diploid I. reichenbachii could be crossed with diploid MTBs. Since these sorts of crosses should produce fertile seedlings, a hybridizer could continue the breeding line to achieve any desired goal.

Iris reichenbachii

I. reichenbachii is a little difficult to find in commerce, but not impossible. Some specialty nurseries list it, and if one is willing to grow from seed, it shows up rather often in seed exchanges that include iris species.

If you see this odd little species available somewhere, why not give it a try? Perhaps even make a cross or two to see what happens...

Iris pumila: a Tiny Treasure

by Tom Waters

Iris pumila

In an earlier blog post, I wrote about how the tiny bearded iris species Iris pumila was imported to the US by Robert Schreiner in the 1930s and crossed with the popular tall bearded irises, giving rise to a whole new type of garden irises, the standard dwarfs (SDBs).

Today, I thought I would write about Iris pumila itself. Besides being an extraordinary find for iris hybridizers, it is a delightfully varied species that makes a wonderful garden plant. It is invariably the first bearded iris to bloom in the spring, starting several weeks before most of the hybrid dwarf cultivars.

In the wild, Iris pumila grows in a wide range across eastern Europe, from Austria in the west through Hungary, Romania, Ukraine, and into the Caucasus Mountains as far as Armenia and even Turkey. It is often found at higher elevations and dry, continental steppe climates. It is adapted to cold winters and sunny, open spaces. Conventional wisdom has it that Iris pumila does best in areas of colder climate (USDA hardiness zone 6 or colder), although I have grown it in southern New Mexico (zone 8), so it may be worth a try even in warmer areas.

Iris pumila is among the tiniest of bearded irises, with the tip of the blooms only about 10 cm from the ground. Usually, the stem is so short as to be hardly detectable; the blooms are held aloft on an elongated perianth tube, so that each bloom seems to be just sitting atop the rhizome from which it grows.

The species shows a phenomenal range of color. To judge from pictures I have seen on the internet, Ukraine seems to be the center of its diversity, with many extraordinary color combinations seldom seen in plants that have been imported to the US or western Europe.

The basic color may be blue, purple, yellow, or white, in any shade from pale to intensely saturated. There is almost always a darker "spot pattern" on the falls, which may be small or may cover virtually the entire petal. The spot may be solid color, or appear as rays or veins or an uneven wash of color.

You can find Iris pumila offered for sale by some alpine or rock garden nurseries. (A word of caution: non-specialist nurseries, like garden centers, often use "Iris pumila" to label any small bearded iris cultivar; these are not the true species.) Many seed exchanges have it, and growing from seed can be extraordinarily fun, since every seedling is different. It does take some patience, however, as irises take 2 to 3 years to bloom from seed.

There are also named cultivars of Iris pumila available from specialty iris growers. Many of these are registered as miniature dwarf bearded (MDB), since they meet the definition of the class. More recently, some have been registered as species (SPEC). One very popular Iris pumila cultivar is 'Little Drummer Boy' (Willott, 1997), which won the Caparne-Welch Medal for best MDB in 2005.

'Little Drummer Boy' (Willott, 1997)

Some newer Iris pumila cultivars include 'Steppe' (J. Burton, 2011), 'Keystone Oracle' (Jesberger, 2011), 'Wild Whispers' (Coleman, 2012), and 'Royal Wonder' (Coleman, 2013). 'Keystone Oracle' is notable for turquoise tones around the beard and spot, which varies from dark to pale depending on climate.

'Keystone Oracle' (Jesberger, 2011)

'Hobbit' (Miller, 2004)

'Royal Wonder' (Coleman, 2013)

I hope I've given you a taste of the beauty and variety of this diminutive iris species. Have you tried growing any Iris pumila in your own garden?

Arilbred medians: irises that have it all

by Tom Waters

'Brash and Bold' (Black, 2009)

In my blog post this April about arilbred irises, I mentioned that these striking garden jewels come in all sizes. Today I'm going to focus in on the smaller arilbreds, which are often called arilbred medians.

All arilbreds have in their ancestry both bearded irises and the exotic aril irises from the mountains and deserts of southwestern Asia. Because tall bearded irises have long been the most popular and extensively bred of the bearded types, it was mostly tall bearded irises that were used to produce arilbreds.

However, there have always been hybridizers of an adventurous bent who used dwarf or median bearded irises to produce arilbreds. Among the first irises from such breeding is 'Zwanenburg' introduced by French hybridizer Louis Denis in 1912. Its parentage is a matter of debate, but a dwarf bearded cultivar derived from Iris lutescens was one of the parents, and there is clearly aril ancestry as well. Remarkably, it is still being grown today! Its muted bronze and gray colors are not to everyone's liking, and the stalks and petals are rather flimsy, but it grows and blooms prolifically and has been delighting gardeners for over a century.

'Zwanenburg'

In the middle of the 20th century, two developments occurred that paved the way for renewed interest in arilbred medians. The first was the development of the modern standard dwarf bearded irises (SDBs) from TBs crossed with the tiny dwarf species Iris pumila (see my blog post in July of this year here). The second was the creation of a "fertile family" of arilbreds from TB and aril breeding. Most earlier arilbreds had been quite sterile, which meant that new ones could only be created by working with the pure arils themselves, which are difficult to grow and breed with. The new fertile arilbreds meant that it was now relatively easy to produce all sorts of new irises with aril ancestry.

Since that time, crossing SDBs with fertile arilbreds has been the most common way to create arilbred medians. They vary a lot in height, but average around 18 inches high. These are only 1/4 aril, so often their aril characteristics are rather subtle. The best have obvious veining or a definite signal patch below the beard, and have a more globular flower form than do the intermediate bearded irises (IBs), which they otherwise resemble.

'Octave' (Johnson, 2008)

'Enigmatic Elf' (Jensen, 2007)

'Suspect' (Johnson, 2006)

Some small arilbreds were also produced by crossing SDBs or dwarf species directly with pure arils. Because they bypass the TB ancestry that comes in when using an arilbred parent, they are both smaller (averaging around 10 inches) and more aril-like.

'Loudmouth' (Rich, 1970)

'Tiny Pirate' (Rich, 1990)

'Vera-Marina' (Ransom, 1998)

Most arilbred medians carry genes from three distinct types of irises: arils, tall bearded, and dwarf bearded (usually Iris pumila), making them one of the most genetically rich types of irises you can grow. They really do have it all! This genetic diversity expresses itself in a wide range of colors and patterns, a wide range in height and garden uses, and adaptability to a range of climates. Their dwarf ancestry helps many of them deal with cool rainy climates better than the taller arilbreds, and conversely their aril ancestry helps them do better in mild-winter climates than the SDBs.

Most arilbred medians are sterile, but there are a few fertile ones from unusual breeding approaches. 'Aladdin's Gem' (Thoolen, 2002) has only Iris pumila and pure arils in its ancestry - no TB heritage at all! Likewise, 'Anacrusis' (Mathes, 1992) is derived from pure arils and the dwarf bearded species Iris suaveolens. It has a number of worthy descendants, including the striking and popular 'Concerto Grosso' (Mathes, 1998), which won the C. G. White Medal in 2005.

'Aladdin's Gem'

'Anacrusis'

'Concerto Grosso'

Have you tried any arilbred medians in your own garden? How do they do in your climate?