Arilpums Are Here!

by Tom Waters

When I last wrote about my progress with hybridizing arilpums in September, I was eagerly anticipating this spring's bloom, with many new seedlings expected to bloom on established plants. I was not disappointed!

Aladdin's Gem

First, a little recap. Arilpums are hybrids between pure arils and the dwarf bearded species Iris pumila. When a tetraploid aril is used as the aril parent, theory predicts that the arilpum seedlings will be fully fertile amphidiploids. Historically, most arilbred dwarfs and medians have been produced by using arilbreds, diploid arils, and SDBs in various combinations, and the result has been infertile offspring, making it impossible to linebreed the smaller arilbreds to refine them and extend their potential. Arilpums are the way out of that difficulty. However, only a few have been registered and introduced: 'Barbarella' (Mathes, 1991), 'Aladdin's Gem' (Thoolen, 2002), and 'Topaz Talisman' (Jensen, 2015). Although producing fertile pollen, arilpums so far have shown little or no pod fertility, a disappointing setback.

Last spring, I had some luck with the two arilpum seedlings I bloomed, Q025-01, 'Merlin's Magic' X Armenian pumila seedling, and Q053-01, 'Tadzhiki Bandit' X 'Sudden Butterflies'. Both produced seeds for me, as did a seedling of George Hildenbrandt's, GH-11-4-2, 'Dunshanbe' X 'Hidden Dragon'. So it seemed there was hope after all for creating a line of fertile arilpums!

This spring reinforced my optimisim, and also gave a preview of the great variety of color, pattern, and form that is possible with arilpums.

Q068-14

Q068-04, with "monster beards"

Earliest to bloom were seedlings from cross Q068, 'Dunshanbe' X 'Wild Whispers'. I had over a dozen of these, most dark violet selfs with some aril look but without much distinctiveness. Two stood out, however. Q068-04 has massive caterpillar beards. Not exactly beautiful, but certainly memorable. Q068-09 is the best of the lot, with a clean oncocyclus shape and elegant look. 

Q068-09, the standout

The second cross to bloom was really exciting: Q066, 'Tadzhiki Bandit' X Caucasus pumila seedling. These were much smaller and more varied than the 'Dunshanbe' seedlings, showing many exciting colors and patterns. I've kept almost everything from this cross for further evaluation.

Q066-06

Q066-02

There was another from cross Q053, looking almost the same as its sibling that bloomed last year. I also had a few seedlings from cross Q070, 'Vera' X 'Royal Wonder', one of which was deemed worthy of a closer look.

Q070-01

I made a number of crosses with this year's arilpums, but was not very systematic or thorough about it. Seeds have not been harvested yet, so it is premature to say much about their pod fertility. But there are pods, even some bee pods, so I am optimistic. 

It's been about ten years work to get to this point, but at last I have a small cadre of arilpum seedlings to work with, and the future looks very promising.

Progress with Arilpums

by Tom Waters

When I wrote my previous blog post on arilpums early in 2019, I had to focus mostly on history and theory, as I did not yet have much to show from my own seedlings. That has now changed, and the current state of this project is even better than I had dared hope.

As explained in the previous post, arilpums are arilbreds dwarfs that come from crossing pure arils with the dwarf bearded species Iris pumila. If the aril parent is a tetraploid, theory says the resulting arilpums should be fertile amphidiploids, a sort of arilbred analog of the SDBs. They thus have the potential of ushering in a whole new "fertile family" of miniature arilbreds.

Waters Q025-01

This spring, I bloomed two arilpum seedlings, both prolific two-year-old clumps covered in bloom. The first, Q025-01, from 'Merlin's Magic' (a selection of Iris stolonifera) x P002-05, a pumila seedling of Armenian origin, has a dainty Regelia look and some nice veining. The second seedling, Q053-01, from 'Tadzhiki Bandit' x 'Sudden Butterflies' is larger and huskier, with flowers reminiscent of tall arilbreds with Regelia ancestry, such as 'Stars Over Chicago' or 'Saffron Charm'.

I also had good bloom this year on an arilpum seedling from

Waters Q053-01

George Hildenbrandt, GH-11-4-2, from 'Dunshanbe' x 'Hidden Dragon'. This is a charming dark arilpum with nice aril-like flower form.

Hildenbrandt GH-11-4-2

The remarkable thing is that all three of these seedling produced seed for me this year when crossed with other arilpums. In my previous post, I mentioned that earlier hybridizers working with arilpums had found them to be infertile as pod parents. That is clearly (and thankfully!) not a general rule! Here are my successful arilpum x arilpum crosses this year:

Q053-01 x Aladdin's Gem gave 38 seeds

Q025-01 x Q053-01 gave 9 seeds

GH-11-4-2 x Q053-01 gave 23 seeds

GH-11-4-2 x Aladdin's Gem gave 3 seeds

These are not huge seed yields, but they are certainly adequate for continued breeding. I am quite optimistic that a number of the second-generation seedlings from these crosses will be fully fertile, and it will be possible to line breed arilpums without having to constantly go back to the difficult aril x pumila initial cross. This will also open up arilpum breeding for hybridizers who live in areas where either arils or pumila are difficult to grow.

Next spring should offer even more excitement, as I have more than 30 arilpum seedlings from various crosses that will be blooming as two-year-old plants. I got a sneak preview of one this spring,  Q066-08, from 'Tadzhiki Bandit' x P018-02, a pumila seedling originating from the Caucasus mountains. It looks for all the world like a miniature rendition of its aril pod parent, giving a rather more "onco" impression than others mentioned in this post. It has not yet been tested for fertility.

Waters Q066-08

All this has been an exciting vindication of a breeding project motivated mostly by theoretic possibilities rather than concrete experience. I'm now confident that arilpums have a bright future ahead.

Russian Hybridizing 2

By Sergey Stroganov

Editor's Note: In this second part, Sergey writes about some other seedlings he enjoyed in his first crop. Any of us who have hybridized know this special thrill when see the first children.

The next cross I liked was 18-73: ‘One of a Kind’ X ‘Mood Ring’. It bloomed almost in full, and most importantly, gave a large variety of fun seedlings with good branching and growth, including a lot of brown seedlings, despite the fact that this color is not common (most likely, these genes are carried by the ‘Mood Ring’?).

Parents first:

‘One of a Kind’

 

‘Mood Ring’

 

18-73A: standards are largely inherited from my mother, and it turned out quite unusual, in my opinion.

 

18-73B: I have already seen a similar color scheme in seedlings. This one won me over with its branching. Well, the combination of blue and brown (on the hangers and border) looks modern.

 

18-73C: now go brown - this brown-gold.

18-73D is lighter in tone and touches are added to the beard.

18-73E: this one impressed me the most of the entire party with its uniqueness.

18-73F did not blossom in full force this time.. also from a series of brown, with a striped iridescence.

18-73H and this color was also present. Note that almost all seedlings on the standards are visible venation, this is from One of a Kind.

18-73I again brown with strokes, apparently created to confuse me.

18-73J - an even richer brown and an even rarer color.

 

 

And finally for today-Seedling 18-343A: 'In the Morning ' X 'Another Suggestion'. From this cross, only 2 seedlings bloomed - the first was unsuccessful, but this one exceeded my expectations and became my favorite seedling this season.

 

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.

News from Amasya

By Sylvain Ruaud

Between the cities of Batumi - in Georgia - in the east, and Sinope in the west, along the Black Sea, stands a coastal strip where the Cappadocia plateau slopes towards the sea. This is now Turkey, but in antiquity, it was a region colonized by the Greeks who founded there several prosperous cities, either by the sea, like the current Trabzon (Trebizonde, in the old days), Sinop ( Sinope for the Greeks), or, above all, Samsun (Amisos), either higher in the foothills of Cappadocia, and Amasya (Amaseia in ancient Greek). Amasya is located in the deep valley of the Yesilirmak river, which wiggles in the region before joining the Black Sea. In antiquity this river was called Iris! Here is a name well predestined for a river which crosses the region where our current tetraploid irises originate.

'Mrs. George Darwin'

'Mrs. Horace Darwin'

Although the city of Amasya was destined to find a prominent place in the small world of irises, it was not until the end of the 19th century and the work of Sir Michael Foster, physiologist and professor at Cambridge, and famous collector of irises that the area became important. He had started iris growing by taking an interest in the oncoclyclus irises, then also in the iris spurias with which he launched into interspecific hybridizations. He also undertook the hybridization of what was then called the Germanica irises and obtained two varieties which remained famous: 'Mrs. George Darwin 'and' Mrs. Horace Darwin 'whom he named as a token of friendship with two of his neighbors. About these varieties we read this in The World of Irises: “They were whites and the first had a touch of gold in the throat that made it stand out from any other. It also had the virtue of being very late and was at its best when most of the other varieties had finished blooming. But fine as these varieties were, Foster agreed with those who said that further improvement of the bearded irises was impossible, or at least improbable, unless new species with new characteristics could be found to use as parents”.

'Lord of June'

But where to find these new species? Foster had heard of iris with huge flowers (for the time) that were found in Asia Minor. He therefore got in touch with missionaries who then went to these regions not only for religious reasons, but also scientific purposes. It was frequently that people of church took advantage of their mission to locate plants, and many of the plants which are today frequent in our gardens come from specimens brought back by missionaries. Michael Foster's emissaries sent him irises, good, mediocre, and uninteresting; but among the good ones there were some who revolutionized the world of bearded irises. Especially a species discovered in the north of Anatolia, in the region of Amasya and baptized for this reason 'Amas'. In fact there were in Great Britain several arrivals of these exceptional irises but none has been precisely described and distributed so that it is not known exactly which is at the origin of what. The varieties that we attribute to the iris 'Amas' may come from another plant, which by the way was perhaps of the same species! The fact remains that the fame of these Anatolian irises returned to 'Amas' and, as a result, to the city of Amasya.

'Amas'

Foster made many seedlings from his 'cluster', but it was not until his death in 1907 that these were brought to the market, among with other hybrids of the same origin obtained by Foster's friend George Yeld. These new plants include 'Caterina', 'Crusader' or 'Kashmir White', from the production of Foster and 'Halo' or 'Neptune' from that of Yeld. All these novelties were not masterpieces and they turned out to be fragile, often affected by rot and not very rustic. In addition, almost all of these varieties were blue-lavender or purple. They were nevertheless successful because of their exceptional dimensions and the hopes placed in them for a renewal of bearded irises.

'Kashmir White'

It took persistence and patience to believe in this revival because it did not appear overnight! The hybridizers tore their hair out when they noticed that the crosses made between these Amasya irises and European irises did not give much: almost no seeds or plants, large, certainly, but sterile and without other qualities remarkable. It was only in the long run, after many unsuccessful attempts, that they obtained hybrids that were both fertile and beautiful. No one knew why. A botanist by the name of Strassburger had observed in 1882 the presence of chromosomes in plants, but this discovery had not aroused any interest. It was only around forty years later that the first chromosome counts revealed the reason why the Anatolian irises, and their rare fertile hybrids, were larger and more beautiful: they had four pairs of chromosomes at the place of the two pairs which characterized the ancient irises.

To fully explain this phenomenon, I have found nothing more perfect than a text written by Ben Hager, the well-known hybridizer, published in the first part of a book of artistic photographs of iris, "L'Iris” from Dutchman Josh Westrich. Here is this explanation:

“All living organisms, plants and animals, are made up of cells. All cells have a common basic structure and each has a nucleus. In only one of its infinitesimal entities are numerous chromosomes grouped together, the number of which varies according to organisms. Chromosomes carry a genetic map that controls the development and characters of the new organism after fertilization. The egg cell produces new cells that are identical in every way and intended to form a completely rejuvenated structure. At the moment when the reproductive cells or gametes are formed in the flower, the number of chromosomes is divided into two equal batches but with, often, a mixing of the characters carried by the chromosomes. Male and female cells from the same parent (self-fertilization) or from different parents, will give egg cells with a different genetic heritage and will produce different plants. (...) "

“Nature prefers simplicity. Individuals resulting from the fusion of two reduced batches of chromosomes are called diploids. But accidents happen: if, during the formation of gametes, the cells do not correctly reduce the number of chromosomes, the egg contains four sets of chromosomes instead of two. Such cells are called tetraploids; because of the accident to which they are due, they have everything in duplicate. "

Why did the first crosses between the irises of Amasya and the “old ones”, originating from our countries, give only disappointing plants? It was that we had mixed tetraploid plants, the "new", with diploid plants, the "old". Hence the production of triploid plants (one batch of chromosomes from the diploid parent and two batches of chromosomes from the tetraploid parent), which are almost always sterile. And if later crosses proved to be superb and fertile, it was because they were, always accidentally, tetraploid, due to an unreduced gamete in a diploid parent. But no one was aware of this in the 1890s at the time of the attempts of Foster and his followers.

Fortunately, the accident described above has occurred often enough for the tetraploidy of the Amasya iris to settle down in a stable fashion and for the varieties obtained from the 1920s to be all tetraploid and to combine the qualities of the iris from Anatolia and those of European hybrids, giving birth to the irises that we know today.

This is why we owe so much to the plants harvested by the missionaries evangelizing the confines of the Ottoman Empire. This is why the region of Amasya and the banks of the Iris river (what a coincidence!) Can be considered as a cradle of modern iridophilia.

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.

Arilpums: Fertile Arilbred Dwarfs!

by Tom Waters

'Aladdin's Gem' (Thoolen, 2002)
OGB/ABD

Most arilbred medians are produced by crossing standard dwarfs (SDBs) with fertile halfbreds (OGB). The results of such crosses tend to be pleasing garden subjects, occupying about the same niche as intermediates (IBs), but with the added interest of arilbred color patterns. Unfortunately, arilbred medians produced this way are usually infertile, or have very limited fertility at best. Also, being only ¼ aril (OGB-), they don’t always show enough pronounced aril characteristics to really stand out as arilbreds.

For those of us who enjoy the smaller arilbreds, the holy grail would be diminutive fertile arilbreds that are half aril in content. We might imagine miniaturized versions of the taller arilbreds that have come from breeding arils with tall bearded (TBs). One approach to realizing this dream is through the creation of “arilpums”: hybrids between arils and the tiny dwarf bearded species Iris pumila. This type of cross produces true arilbred dwarfs, around 10-12 inches (25-30 cm) in height, fertile, and half aril. Additionally, Iris pumila is expected to confer winter hardiness on its seedlings.

The potential of such breeding was first appreciated in the mid 20^th century, when iris breeders became aware of the cytogenetics of irises, and the possibility of creating “fertile families” of irises from wide crosses, if the parents are chosen to have the right chromosome configurations to produce fertile offspring. Both the SDBs (from TBs crossed with Iris pumila) and the fertile arilbreds (from TBs crossed with arils) are examples of such fertile families, and show how varied and successful they can be.

The most direct way to build a fertile family of arilpums is to cross Iris pumila with tetraploid arils. In nature, the only tetraploid arils are the Regelia species Iris hoogiana and Iris stolonifera. Indeed, the pioneering hybridizer Paul Cook (who also introduced the first SDBs from TB x pumila crosses) produced two hoogiana/pumila hybrids in the 1950s: ‘Hoogpum Blue’ (Cook, 1956) and ‘Hoogpum Purple’ (Cook, 1956). Both were fertile, but Iris hoogiana doesn’t have many characteristics that most of us think of as epitomizing the “aril look”, and these little offspring were not very distinguishable from MDBs, and in fact were registered as such.

The first approach to arilpums with oncocyclus ancestry came from Peter Werckmeister, the great expositor of cytogenetic theory to English-speaking irisarians. In the 1970s, he produced “Miltonia” (not registered) from a lucky cross, in which the aril parent (an oncogelia from ‘Teucros’ x Iris susiana), although a diploid, acted as a tetraploid by producing an unreduced gamete. Werckmeister reported eventually creating a whole array of fertile arilpums from “Miltonia”. Alas, they were not widely distributed and are now lost to us.

Thoolen arilpum seedling AP9007-1

Interest in arilpums underwent something of a revival in the 1990s, after Samuel Norris and John Holden created a line of tetraploid oncogelias from using colchicine treatment. Crossing these with Iris pumila produced arilpums with much more “onco look” than had been possible previously. The first of these to be introduced was ‘Barbarella’ (Mathes, 1991), followed by ‘Aladdin’s Gem’ (Thoolen, 2002). Both Harald Mathes and Francesca Thoolen raised a number of different arilpum seedlings, but these were the only two registered and introduced into commerce. Both ‘Barbarella’ and ‘Aladdin’s Gem’ produce fertile pollen, but are unwilling pod parents. Mathes and Thoolen noted similar difficulties with their other arilpums, and their breeding programs were eventually abandoned.

The lack of pod fertility was an unfortunate setback, because the simplest way to build up this family would be to cross the existing arilpums among themselves, rather than repeating the initial aril x pumila crosses.

'Topaz Talisman' (Jensen, 2015)
RB/ABD

The most recent arilpum is the lovely stolonifera/pumila hybrid ‘Topaz Talisman’ (Jensen, 2015). It has not yet been tested extensively for pod fertility.

Why has this family not made more progress? It has been more half a century since its potential was first understood, theoretically. I do not believe the pod fertility issue is insurmountable, although it is a setback and perhaps kept the family from taking off in the 1990s, when interest was greatest. Since then, the number of hybridizers working with arilbreds has declined, and not all are interested in such an experimental project. The parent plants, tetraploid arils and Iris pumila, are not easy to grow in all locations: the arils need a very dry summer, and pumila needs a cold winter.

Another obstacle is that the initial crosses are difficult, not many viable seeds are produced, germination is poor, and so a lot of persistence is needed to bring arilpum seedlings to bloom. Since I began working in this area six years ago, I have made 365 pollinations, resulting in 525 seeds, and at long last four seedlings which I hope to see bloom this year or next.

I would love to see others get involved; the prospects for eventual success obviously depend on a number of people working with determination over the course of a number of years. Here is the recipe:

1. Acquire tetraploid arils, such as Iris stolonifera, ‘Tadzhiki Bandit’, ‘Tadzhiki Eclipse’, ‘Werckmeister’s Beauty’, ‘Balalaika Music’, and ‘Dunshanbe’. Keep in mind that you must use tetraploid arils – crossing Iris pumila with random arils and arilbreds offers no special hope of fertility in the seedlings.
2. Acquire Iris pumila, either from seed exchanges, or named cultivars such as ‘Royal Wonder’, ‘Wild Whispers’, ‘Little Drummer Boy’, ‘Hobbit’, and others.
3. Make crosses between these two groups, as often as possible, and mixing and matching parents as much as possible.
4. Also get any available arilpums (pretty much just ‘Aladdin’s Gem’ and ‘Topaz Talisman’ these days), to cross amongst themselves or with arilpum seedlings you produced from the aril/pumila crosses.

Hildebrandt arilpum seedling 11-4-2
(photo: George Hildebrandt)

I think this a project that offers enormous potential in the long term, and is ideal for a small, backyard hybridizer who does not have the resources to grow thousands of seedlings and does not need to worry about immediate commercial success. There is a whole new world waiting to be opened up!