The Aril Society Checklist

 by Tom Waters

When I'm not writing blog posts, one of my many other iris-related activities is serving as checklist editor for the Aril Society International. I've just completed the 2023 update of the checklist, which is available on the ASI website. It occurred to me that there are probably many people who are not aware that the ASI maintains a checklist of aril and arilbred irises, nor aware of what it offers beyond other references. So I thought I would use this blog post to have a look at the checklist and why it is important.

When the Aril Society International was formed in the 1950s, there were no standardized definitions for the various types of aril and arilbred irises. Irises with oncocyclus or Regelia ancestry were registered with the American Iris Society under a bewildering range of classification codes. One of the first tasks of the new society was to sort through all the various registrations and establish specific categories for them. A persistent problem in the early years was that irises of 1/8, 1/16, or even less aril ancestry were being given awards as arilbreds despite being indistinguishable from TBs. The society addressed this by requiring irises to be 1/4 aril or more to be considered as arilbreds. Subsequently, there were two separate award systems created: one for arilbreds of 1/4 to 1/2 aril content, and another for irises of 1/2 aril content or more.

'Loudmouth' (Rich, 1970) won the
C. G. White Award as an OB (1/2 aril)
but is now an OB- (less than 1/2) 
because of a change in definition.

The checklist was critical for establishing which irises met the various award criteria. The editor would take the registration data, do pedigree research, consider an iris's appearance, breeding behavior, and any chromosome counts that had been done, and then assign it to the appropriate category. In days before the internet, the ASI checklist was the only source of this classification information, because it was impractical to reprint the American Iris Society checklists to give updated classifications for arilbreds. The classifications and definitions used by the Aril Society have changed several times over the years, and the checklist is the only authoritative reference on how definition changes have affected the classification of each arilbred iris. Applying the current definitions, which involve estimating the chromosome makeup of each cultivar, is not a trivial matter in some cases.

Here are some of the things you will find in the ASI checklist that may not be presented accurately (or at all) in other sources:

Classification Information. Each iris listed, even historic irises registered long ago under other definitions, are assigned to the current ASI classification, to the extent possible given the existing information. This is of particular value to show classification committees in regions where arils and arilbreds are likely to be exhibited. It is especially important for irises that were once considered arilbreds, but no longer meet the definitions of that class.

Height Categories. In 2018, the ASI established definitions for two height categories for smaller arilbreds: arilbred dwarf (ABD) and arilbred median (ABM). These are included in the current edition of the AIS Judges' Handbook. The checklist gives the correct height category for each arilbred listed.

Chromosome Configuration. Aril and arilbred irises may include chromosome sets from oncocyclus, Regelia, tall bearded, and dwarf bearded species. Which chromosome sets are present in a given iris is of considerable interest to hybridizers, as it affects fertility and helps the hybridizer properly classify any resulting seedlings. The checklist provides the most likely chromosome configuration for most irises listed, along with an actual chromosome count where one has been reported.

Fertility Observations. When an iris is known to have produced offspring as a seed parent or pollen parent, this is noted in the checklist.

Is this 'Bronze Beauty',
'Hoogiana Bronze Beauty',
Iris hoogiana 'Bronze Beauty',
'Bronze Beauty Van Tubergen',
or 'Antiope'? Answer: yes.

Irises Not Eligible for Awards as Arilbreds. An appendix to the checklist provides a thorough listing
of irises that do not qualify as arilbreds for various reasons: never having been registered, having been registered in a non-arilbred class, or having been disqualified as definitions became more strict.

Nonregistered Aril Hybrids. A substantial number of aril hybrids have been introduced, particularly through the firm of Van Tubergen in the Netherlands, that were never registered with the American Iris Society. Some were registered with the Dutch registration authority for bulb irises, while others were simply not registered at all. The checklist includes these in an appendix, along with photographs and other information.

Even today, where so much information seems just clicks away on the internet, the ASI checklist fills an important role in providing authoritative information that is not reliably available elsewhere. It is an important resource for judges, show officials, and hybridizers. Anyone with an interest in aril and arilbred irises should become familiar with what the checklist has to offer.

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.

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

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!

In Praise of Regelias

by Tom Waters

The Regelias are a group of irises native to central Asia, their range extending from near the Caspian Sea to the mountainous regions bordering Tibet. Their nearest relatives are the oncocyclus, which are found further west and south from western Iran to the Mediterranean. Regelias and oncocyclus together comprise the aril irises.

First, a few comments on the name "Regelia". The name honors German botanist Eduard August von Regel, who was director of the botanical garden in St. Petersburg, Russia, late in the nineteenth century. Russian plant explorers of that time were very active in central Asia, seeking out new species and bringing them to attention of European botanists and gardeners. The proper pronunciation of the name is thus Reh-GEH-li-a, although most English speakers have taken to using the pronunciation Reh-JEE-li-a instead. The name should be capitalized, since it comes from a personal name. Spell-checking software likes to change the name to "regalia", which refers to Royal trappings, a blunder that one should be alert for.

Regelias are similar to oncocyclus in having a large cream-colored aril attached to the seed, in going completely dormant in summer, and in preferring arid conditions. Whereas oncocyclus iris have only one bloom per stalk, Regelias usually have two. Regelias have beards on the inside of the standards as well as the falls! Whereas many oncocyclus have large globular blooms with prominent signals, Regelias have more svelte, elongated flowers, often with conspicuous veining. The two groups are interfertile, and there are advanced-generation hybrids between them.

There are eight or more species of Regelias. Historically, the three species grown in European and American gardens were the diploid Iris korolkowii and the tetraploids I. stolonifera and Iris hoogiana. More recently, I. afghanica and I. lineata are also sometimes obtainable. W. R. Dykes regarded Iris hoogiana as the most beautiful of all irises, because of its satiny sheen and elegant form.

Iris hoogiana

Iris stolonifera

'Vera' (RH)

There are hybrids between the Regelia species, called Regelia hybrids (RH). Two widely known Regelia hybrids are 'Vera' (uncertain parentage, derived from Iris stolonifera, probably crossed with Iris korolkowii), and 'Bronze Beauty Van Tubergen', a stolonifera/hoogiana hybrid registered by the Aril Society International in 2001, but in commerce since the mid-twentieth century.


All Regelias are adaptable to a wider range of climatic conditions than their oncocyclus relatives. Here in northern New Mexico, mine persist better than daffodils, and get the same care. Cold winters present no problem whatsoever, as they are native to continental mountainous regions. Dampness and humidity in summer can cause problems, as the plants are dormant then and susceptible to rot.

Regeliocycli

'Bronze Beauty Van Tubergen' (RH)

Once it was understood that the Regelias and oncocyclus irises could be crossed readily, hybridizers became interested in such hybrids, mostly as way to breed the Regelia adaptability into the often troublesome oncocycli, which are notoriously particular and difficult to grow in many climates. The firm of Van Tubergen produced a number of regeliocyclus hybrids in the early 20th century, many of which indeed proved quite durable and are still enjoyed today. Most of these were produced by crossing Iris korolkowii with oncocyclus species, and showed both Regelia veining and oncyclus dotting and signals. In current usage, the term "regeliocyclus" (RC) refers to a hybrid with both Regelia and oncocyclus ancestry that is predominantly Regelia in appearance. In practice, regeliocycli are aril hybrids with 1/2 Regelia ancestry or more.

'Dardanus' (Van Tubergen, not registered) (RC)

Regeliabreds

When hybridizing interest in arils blossomed in the 1940s and 1950s, the attention was almost exclusively on the oncocyclus. Regelias were thought of as "poor relations" that were not always welcome at the table. The prevailing opinion at the time was that they might be useful in breeding arilbreds that were easier to grow, or to facilitate breeding oncocyclus with bearded irises, but it was the "onco look" that was the holy grail of arilbred breeders, and signs of Regelia ancestry were frowned upon.

'Stars Over Chicago' (H. Danielson, 1973)

Henry Danielson was among the first to produce and promote arilbreds of purely Regelia ancestry, launching a popular series of regeliabreds with 'Genetic Artist' (H. Danielson, 1972). These regeliabreds (RB) were derived mostly from I. stolonifera and I. hoogiana. Rather than the globular oncocyclus look expected of arilbreds at the time, they tended toward elongated, open form, showing off the often dramatic colors of the insides of the standards. Although I. stolonifera itself tends to brownish and muted violet tones, its arilbred descendants often combine gold or yellow color with lavender or electric blue flushes in the center of the falls and standards, with similarly colored beards. These unconventional arilbreds were welcomed enthusiastically by some, but reviled by others as garish departures from the oncocyclus ideal.

In the 21st century, French hybridizer Lawrence Ransom picked up the torch of regeliabred breeding, using the Regelia hybrid 'Vera' to produce the siblings 'Eastern Blush' (2002) and 'Eastern Dusk' (2010). 'Eastern Dusk' then gave the distinctive horned arilbred 'Poisonous' (Ransom, 2010).

'Poisonous' (RB-)

Ransom also produced a delightfully varied series of regeliabred arilbred medians, again using 'Vera' as the Regelia parent, with mixed SDB pollen. These "Vera girls" include the widely grown 'Vera-Marina' (Ransom, 1998) and 'Vera-Ruby' (Ransom, 1996).

A special favorite of mine is an arilbred dwarf regeliabred from I. stolonifera X I. pumila, 'Topaz Talisman' (Jensen, 2015), from long-time Regelia enthusiast Elm Jensen, registered at 10 inches in height.

'Topaz Talisman' (RB)

Regelias and their regeliabred descendants have attracted a devoted following over the years, and have shown their great potential in adding variety, interest, and ease of culture to a collection of arils and arilbreds. Much of their full potential, I believe, is still untested. For decades, they have suffered from unfair comparison with their more popular oncocyclus and oncobred cousins. As more growers and hybridizers move away from the prejudices of the past, the Regelias and regeliabreds may at last come into their own as fascinating and beautiful types of iris in their own right.

Aril Trek 2018!

by Tom Waters

'Point Well Taken' (McAllister, 1998)
at the Pountney garden

On April 6 and 7, aril and arilbred enthusiasts from parts far and wide converged on Las Cruces, New Mexico, to enjoy each other's company and an astonishing array of arilbreds in bloom.

The Aril Trek was a joint undertaking of the Aril Society International and the Mesilla Valley Iris Society, and the arrangements were all excellent and smoothly executed.

A labyrinth patterned after the one at Chartres Cathedral,
in Howard Dash's garden

Friday evening registration was followed an educational session of "aril bingo" and a panel discussion with Dell Perry, Pete McGrath, Rick Tasco, Perry Dyer, and (much to my surprise) yours truly.

'New Vision' (Tasco, 2012)
at the Dash garden

At the Wilson Garden

The heart of the weekend was four garden tours on Saturday: the small but beautifully designed Pountney garden in the residential Tortugas area south of Las Cruces, the expansive Dash garden high in the West Mesa desert, the glorious Wilson Garden north of the city, with row upon abundant row of perfectly grown irises of many types, and the delightfully ornamented Ayres garden, northeast of the city.

The timing seemed perfect for arilbreds, with both halfbreds and quarterbreds apparently near peak bloom, amidst late medians and early TBs. I got to see many old and new cultivars in bloom that I have not grown myself. It was also rewarding to see such fine arilbred performance in gardens with such different growing conditions: desert sand to river-valley clay, cool verdant niches to sites exposed to the full sun, wind, and temperature extremes of southern New Mexico.

'Dubai' (Johnson, 2013)
at the Wilson Garden

Saturday afternoon featured informative judges training led by Dell Perry (who took us through the intricacies of aril and arilbred classification and characteristics with verve and expertise) and Perry Dyer (who applied his experience and keen eye to show how to look at these varied plants in the garden). Yes, I did pass the test at the end!

'Gideon's Lamp' (McGrath, 2004)
at the Wilson Garden

At the Saturday night dinner, keynote speaker Pete McGrath amazed us all with slides of startlingly beautiful pure aril hybrids and tantalizing arilbred seedlings from his continuing effort to bring bolder veining into this group. Pete's talk was also a story of his experience with aril and arilbred irises, full of deep disappointments and unexpected rewards, and always coming back to the personal dimension: the people and relationships that affected him and his work, often in profound ways.

'Mean Mr. Mustard' (McGrath, 2010)
at the Ayres garden

It was a great weekend. I particularly enjoyed renewing old acquaintances in the iris world, and meeting other new friends I had only known on line. If you are an iris lover, but not sure if you can manage the time and expense of attending a national convention, regional and special-interest gatherings such as the Aril Trek are a comfortable and rewarding way to see some beautiful iris gardens and meet many wonderful people!

Arilbred Irises: A Little History

Tom Waters

'Brash and Bold' (Black, 2009),
William Mohr medal 2106
(arilbred median)

The story of arilbreds begins in the late 19th century, when the exotic aril iris species of the Middle East found their way into the gardens of European plant enthusiasts. Sir Michael Foster, England's foremost iris expert at the time, tried his hand at crossing the arils with the more familiar tall bearded (TB) irises. His motives were mainly exploratory; at the time, no one knew if the arils and bearded irises were compatible, or whether desirable garden plants might result from crossing them.

Although these early arilbreds were interesting plants, showing features of both parents, they were also quite sterile. Arils and TBs were just too distantly related to produce fertile offspring when crossed. One might expect hybridizers to simply give up on the idea, but many kept trying. The allure of the arils, with their huge globular blooms, often strikingly marked with velvety signals, veins, and stippling, was not something to be lightly set aside. Also, the arils themselves were difficult to grow in England and much of the US, demanding very dry conditions when dormant in summer and winter. So the great hope was that crossing arils with TBs could produce an aril-like bloom on a plant that could grow in any garden where TBs grow.

The famous iris breeder William Mohr, working in California, produced an arilbred iris that seemed close to fulfilling this dream. Named for him posthumously in 1925 by his friend and fellow iris expert Sidney Mitchell, the iris 'William Mohr' was an instant sensation. Its large blooms and wide falls, inherited from its aril parent Iris gatesii, proved irresistible in an era when most TBs had relatively small, narrow flowers.

'Elmohr'

Like the other arilbreds of similar pedigree, 'William Mohr' was essentially sterile. But it was so popular that hybridizers all over the country kept making crosses with it, ever hopeful. And occasionally 'William Mohr' would reward such persistence by producing a seed or two. We now understand that these seeds were the result of unreduced gametes, where an ovule is produced by bypassing the normal cell division. Usually it was TB pollen used in making these crosses, so the resulting seedlings were 1/4 aril. 'Mohrson' and 'Grace Mohr' were the first introduced, in 1935, launching a tradition of working "Mohr" into the name of these arilbreds. One of these, 'Elmohr' (P. A. Loomis, 1942) became the first and only arilbred to win the Dykes Medal. In this way, William Mohr became associated with the "quarterbreds" (arilbreds of 1/4 aril ancestry), even though he himself never produced any irises of this type.

Although less widely appreciated than the famous 'William Mohr', there was actually one truly fertile arilbred in cultivation at this time, 'Ib-Mac' produced by the Dutch firm of Van Tubergen and introduced in 1910. Unreduced gametes were once again involved, as its aril parent Iris iberica produced an ovule will two sets of aril chromosomes instead of the usual one. 'Ib-Mac' thus ended up as a balanced tetraploid, with two sets of aril chromosomes and two sets of bearded chromosomes, a configuration that is usually fertile.

Crossing 'William Mohr' with 'Ib-Mac' produced the fertile arilbred 'Capitola' (Frank Reinelt, 1940). Many hybridizers now began using 'Capitola' pollen on TBs, a much surer way to produce quarterbreds than hoping for the occasional seed from 'William Mohr'. These quarterbreds were also colloquially referred to as "Mohrs".

The frustration for hybridizers of this era was that although one could produce quarterbreds by crossing 'William Mohr', 'Ib-Mac', or 'Capitola' with TBs, there was no easy way to get more arils into the mix. The quarterbreds only showed moderate aril characteristics, and did not go very far in capturing the appeal of the aril species themselves.

'Oyez'

The great breakthrough in arilbred breeding came from the work of Clarence G. White in the 1940s. Based in southern California, he was able to grow many pure arils and use them extensively in his hybridizing. His early hybrids, such as the perennially popular 'Oyez' (White, 1938), were infertile diploids, but eventually fertile arilbreds began to appear among his seedlings. The first to be introduced was 'Joppa Parrot' (White, 1948). In the decade that followed, a steady stream of fertile arilbreds in a remarkable range of colors and patterns issued from White's garden. We do not know exactly how this happened, because by this time White had given up on keeping records of his crosses, claiming it took too much time away from making the actual crosses. Most likely it was the sheer volume of his breeding program that made these breakthroughs possible. With an enormous number of seedlings, even unlikely events such as unreduced gametes are bound to happen from time to time. The fertile C. G. White arilbreds were later shown to be balanced tetraploids (like 'Ib-Mac' and 'Capitola') with two sets of aril chromosomes and two sets of TB chromosomes.

The 1950s saw the founding of the Aril Society International (ASI). Despite the name, its membership was largely concentrated in southern California, with a few in New Mexico and elsewhere. The ASI in its early years provided a much-needed framework for defining the arilbred class and encouraging the breeding of arilbreds with clear, strong aril flower characteristics. To be classified as an arilbred, an iris could have no less than 1/4 aril ancestry. Hybridizers had often crossed the early quarterbreds back to TBs, sometimes for several generations, promoting the progeny as "arilbreds", although their aril genes had in most cases dropped by the wayside, leaving plants that were for all intents and purposes just TBs. The ASI cooperated with the American Iris Society to establish the C. G. White award for best arilbred in 1961. In 1969, the William Mohr award was added for arilbreds of less than 1/2 aril ancestry, restricting the C. G. White award to those that are 1/2 or more aril. This further encouraged hybridizers to focus on arilbreds with strong aril characteristics. Both these awards attained medal status in 1993.

With the "fertile family" of C. G. White arilbreds firmly established, arilbred breeding at last came into its own. As breeders continued to work with these fertile arilbreds, they improved both in gardenability and in the form, color, and pattern of the flowers themselves. The original C. G. White hybrids typically had only a small diffuse signal patch, and veining that was indistinct and blended. Through the extended effort of dedicated arilbred hybridizers, we now have arilbreds with huge, dramatic signals, striking crisp veining, and an extraordinary range of bright clear colors.

'Anacrusis'

Most fertile arilbreds today derive almost entirely from the original C. G. White introductions. A few notable additions to the family appeared subsequently: 'Welcome Reward' (Sundt, 1971), Henry Danielson's fertile regeliabreds such as 'Genetic Artist' (Danielson, 1972), and Harald Mathes's fertile arilbred medians beginning with 'Anacrusis' (Mathes, 1992). Fertile arilbred seedlings produced by Samuel Norris from his tetraploid arils crossed with TBs also appear in the pedigrees of some modern arilbreds.

The fertile "C. G. White type" arilbreds have also opened up other new areas of arilbred breeding. Crossed with TBs, they have given us quarterbreds that are much more aril-like than the old "Mohrs", and crossed with the standard dwarf bearded (SDB) irises, they have produced the charming arilbred medians, which are at least as popular as the taller quarterbreds today.

The history of arilbred breeding has progressed from an early period of difficulty and frustration, through the breakthrough of C. G. White's "fertile family" to a modern era of continual improvement and expanding diversity. What will the future bring?

Classifying Aril and Arilbred Irises

by Tom Waters

If you're even a little interested in arils and arilbreds, you will have noticed that there is a rather bewildering array of terms used to describe them in catalogs, in iris society publications, and in general use among iris growers. In today's post, I hope to help make sense of it all.

The Big Distinction

The most important distinction of all is that between arils and arilbreds. By today's definition, an aril is a species from the oncocyclus or Regelia sections, or a hybrid derived only from these two groups of species. In contrast, an arilbred is a hybrid derived from both arils and ordinary bearded irises (whether tall bearded, median, or dwarf).

Although this seems pretty easy, and these definitions have been official for more than half a century, one still often hears people casually refer to both arils and arilbreds as "arils". This creates a truly unfortunate confusion, especially since arilbreds differ from arils in both appearance and cultural requirements. To emphasize the distinction, you will sometimes hear people speak of "pure arils" to clarify that they are not talking about arilbreds.

A Closer Look at Arils

Aril hybrids are hybrids whose ancestry is only oncocyclus, Regelia, or both. A hybrid with only oncocyclus ancestry is an oncocyclus hybrid (OH), one with only Regelia ancestry is a Regelia hybrid (RH). Simple enough. But there are two terms in use for hybrids that are a mixture of oncocyclus and Regelia: regeliocyclus (RC) and oncogelia (OG). Originally, these terms indicated whether the cross used to produce the hybrids was Regelia x oncocylcus or oncocyclus x Regelia, but that turned out to be an unhelpful distinction. The appearance of the flowers doesn't depend on which direction the cross is made, and once you have advance-generation hybrids, the distinction is impossible to maintain. Today, we use RC to refer to aril hybrids where the Regelia influence is predominant (these are typically 1/2 Regelia or more by ancestry, but it really depends on the appearance of the flower, not the details of the pedigree). OG, naturally, refers to a hybrid where the oncocyclus influence is predominant.

Iris acutiloba lineolata, an oncocyclus

Iris stolonifera, a Regelia

A Closer Look at Arilbreds

Long ago, people used the word "arilbred" to refer to any iris with both aril and bearded ancestry, regardless of how little aril ancestry or aril flower characteristics it had. Today we know that inheritance is through chromosome sets, and a set of chromosomes is usually either passed on to a hybrid as a complete set or not at all. So many older "arilbreds" that were 1/8 or 1/16 aril by ancestry really had no aril content at all!

One of the first initiatives of the Aril Society International after it was formed in the late 1950s was to restrict the definition of arilbreds to irises with significant aril ancestry and significant aril appearance. Today, to be classified as an arilbred, an iris must be at least 1/4 aril by chromosome complement and the flower must show at least two aril characteristics, such as signal or veining. This definition helps protect the distinctiveness of arilbreds as a class.

Another initiative of the Aril Society was to encourage hybridizers to work with arilbreds that had more aril content and appearance. A separate category was created for arilbreds that are at least 1/2 aril, and these are eligible for a special award, the Clarence G. White Medal. Those less than 1/2 aril are eligible for the William Mohr Medal instead. Unfortunately, there is no simple terminology to distinguish these two categories; you just have to say "less than 1/2 aril" and "1/2 aril or more".

One peculiarity of this division is that aril hybrids (pure arils) are also eligible for the C. G. White Medal, because not enough of these are produced or widely grown to merit their own system of awards. I think this has contributed in a small way to the confusion between arils and arilbreds - for a number of years, the American Iris Society used the abbreviation "AR" for both arils and arilbreds eligible for the C. G. White Medal, and "AB" for arilbreds eligible for the William Mohr Medal.

Nine Types of Arilbreds? Yes, Really

Although for awards purposes, the American Iris Society sorts all arilbreds into only two classes (less than 1/2 aril and 1/2 or more aril), the Aril Society uses a more detailed system of categories that tracks not only the amount of aril content, but also the type of aril content (oncocyclus, Regelia, or both).

An arilbred with only oncocyclus and bearded ancestry is an oncobred (OB). One with only Regelia and bearded ancestry is a regeliabred (RB). If both oncocyclus and Regelia ancestry are present, it is an oncogeliabred (OGB). This is by far the largest category.

If the arilbred has less than 1/2 aril content, it is marked with a "-" sign. If more than 1/2, with a "+" sign. If it has 1/2 aril content exactly, neither a "-" or "+" is used.

So all together that makes nine types of arilbred: OB-, OB, OB+, OGB-, OGB, OGB+, RB-, RB, and RB+.

'Bhutan' (Tasco, 2010), an OGB

'Jeweled Veil' (Rich, 1978), an OGB+

A point to note is that since 1990, the amount of aril content is based on chromosome sets, not parentage (which is why the word "content" is used rather than "ancestry"). Although the distinction between chromosome content and ancestry often makes no difference, there are times when it does. 'Loudmouth' (Rich, 1970), for example, came from a cross of an oncocyclus with an SDB. Thus it is 1/2 aril by parentage. However, the oncocyclus parent was a diploid, providing only one set of aril chromosomes, whereas the tetraploid SDB parent provided two sets of bearded chromosomes, making 'Loudmouth' only 1/3 aril by chromosome content. It won the C. G. White award under the old parentage system, but today it is classified as OB-, and would not be eligible for that award.

'Loudmouth', an OB-

Despite all this attention to detail regarding the aril ancestry of arilbreds, no distinctions at all are made regarding the type of bearded ancestry, whether TB, dwarf, or median. Sometimes smaller arilbreds with dwarf or median ancestry are called "arilbred medians", "aril medians", or other similar terms, but these are not official categories.

Finally, here is a chart that tries to make sense of this all:

I hope this post has shed some light on a rather complicated subject. Do you find these categories helpful when choosing and growing arils and arilbreds?

Tetraploid Arils, Anyone?

by Tom Waters

'Tadzhiki Eclipse'

If you're a gardening enthusiast with a keen interest in irises or other perennials, you've probably come across the term tetraploid. There are tetraploid daylilies, for example, and in the iris world you'll see the term used to describe some miniature tall bearded (MTB), Siberian, and other types of iris. But what is a tetraploid and why does it matter if a variety is tetraploid or not?

Plants and animals are made up of cells, and in the nucleus of each cell are structures called chromosomes that carry the organism's genes. These chromosomes come in sets. For almost all animals and many plants, there are two sets of chromosomes in each cell. Humans, for example, have two sets of chromosomes, 23 in each set. At conception, each person receives one set of chromosomes from their mother and one from their father. One can't really think of any simpler way for an organism to inherit genes from both parents.

There are more complicated ways, however, especially in the plant kingdom. Some plants have four sets of chromosomes, two sets coming from each parent instead of one. These are tetraploids. (Plants with just two sets are called diploids.)

What are the consequences of having four sets of chromosomes instead of two? One consequence is that tetraploids are frequently (not always) larger than their diploid counterparts. In the 19th century, garden tall bearded irises were all diploids. Around 1900, plant collectors found tetraploid tall bearded species in the Middle East, and brought them into European and American gardens. The new plants attracted attention because of their taller stems and larger flower size. (There was no knowledge of chromosome numbers at the time, so iris growers and breeders were aware only of the difference in appearance of the new plants.)

The tetraploids were so popular with iris breeders that by the middle of the twentieth century, virtually all new TB varieties were tetraploid. This is still the case today.

One must be cautious, however, in associating tetraploids with large size. Size is determined by many factors. One of the very smallest bearded irises, the dwarf species Iris pumila, is a tetraploid although the blooms are only a few inches above the ground!

The great importance of tetraploidy in plant breeding is not that tetraploids are sometimes larger, but rather that more genetic combinations are possible with tetraploids than with diploids. With four copies of every gene instead of two, there are just many more possibilities!

One extraordinary aspect of tetraploid breeding is that hybrids between different species or types may be fertile if the parents are tetraploid, but sterile if the parents are diploids. The standard dwarf bearded irises (SDBs), for example, are fertile hybrids between tetraploid TBs and the tetraploid dwarf Iris pumila. So tetraploidy makes possible whole new types of fertile hybrids that simply could not exist otherwise. This is the main reason some hybridizers have taken such an interest in tetraploids.

'Bronze Beauty Van Tubrgen'

So now we come to the topic of this post: tetraploid arils. I love aril irises, with their exotic color patterns and dramatically shaped blooms. Most aril species are diploids. (I'm referring to pure arils here, not the arilbreds, which are a mix of aril and bearded ancestry.) In fact, the oncocyclus arils (the type that usually comes to mind when one thinks of arils) are all diploid. Crossing them with bearded irises, when it can be done at all, produces sterile hybrids.

Think of the possibilities that could open up if there were a family of tetraploid arils, like the family of tetraploid TBs!

Aril hybridizers have been thinking of that possibility for decades, and there are in fact some tetraploid arils, just not very many yet.

First, although all the oncocyclus species are diploids, there are two Regelia species that are natural tetraploids: Iris hoogiana and Iris stolonifera. A classic hybrid from these two species, 'Bronze Beauty Van Tubergen' (Van Tubergen, R. 2001) is also tetraploid. These are all lovely irises, but being Regelias, they do not have the oncocyclus characteristics, like huge globular blooms and big velvety black signals, that are the allure of aril irises for most people.

'Dunshanbe'

Second, a few arils with some oncocyclus ancestry are "accidental" tetraploids. Occasionally, a diploid parent produces a tetraploid seedling by chance. 'Persian Pansy' (Austin, 1960) and 'Tel Hashi' (Kellie, 1968) came about this way, but both seem to be lost now. 'Dunshanbe' (Wilkes, 1977), a seedling of 'Persian Pansy', is still being grown however, and is quite lovely with a dark sheen and nice veining. Its makeup is still more Regelia than oncocyclus, however.

Third, some breeders have created tetraploids deliberately using the chemical colchicine, that interferes with cell division, sometimes converting a diploid plant to a tetraploid. Usually, the plants created this way are unstable and sometimes unhealthy, but they can be crossed with other tetraploids to produce stable, reliable plants. 'Werckmeister's Beauty' (Werckmeister, 1992) came from this approach. In the 1980s, Sam Norris and John Holden created many tetraploid arils of predominantly oncocyclus makeup using this method. Alas, few have survived to the present day, and none are available commercially. Lawrence Ransom used one of these to produce 'Tadzhiki Eclipse' (Ransom, 1997) and 'Tadzhiki Bandit' (Ransom, 1997), both of which are still being grown in Europe and the US. 'Tadzhiki Eclipse' is, I think, the most oncocyclus-like tetraploid aril one is likely to be able to acquire today.

'Werckmeister's Beauty'

Through a little patience and diligence, I have acquired a small collection of tetraploid arils from the plant sale of the Aril Society International, occasional offerings of commercial growers, and the generosity of fellow aril hobbyists. I encourage others to do the same, especially those who live in the western US or other regions where pure arils can be grown without heroic measures being taken on their behalf. These are arils, not arilbreds, so they may need a little special attention regarding soil and siting. I have found them easier than most other pure arils, however.

If you are a hybridizer, you can cross them with each other to expand the family, or cross them with tetraploid bearded irises to create brand new types of fertile arilbreds.

Even if you are not a hybridizer, you can enjoy their bloom and know that you are helping preserve a very important group of plants, which may someday become the progenitors of new breeds of irises we can only imagine today.

If you can grow aril irises, have you tried any of the tetraploids? I think they are worth seeking out.

'Tadzhiki Bandit'

Arilbred Irises: A Touch of the Exotic

by Tom Waters

One of my favorite types of iris is hardly known to the general gardening public: arilbreds. These striking plants are deserving of much more attention.

What is an arilbred? The term aril applies to two groups of irises: the oncocyclus from the Middle East, and the Regelias from central Asia. (The word "aril" is a term for the prominent white color seen on the seeds of these types of iris.) These aril irises, although some of the most spectacular flowers in the genus Iris, often proved difficult to propagate and maintain in northern Europe or the US. Arilbred irises are the result of crossing these aril irises with the more familiar bearded irises. Many earlier breeders making these kinds of crosses were dreaming of flowers like those of the aril irises on plants that were as easy to grow as bearded irises. Today, this dream has largely become reality. Along the way, the endless gene combinations gave rise to a huge variety of flower types not even imagined before.

Seeds of an oncocyclus iris. Note the fleshy white collar or "aril", from which aril irises take their name.

Arilbred irises come in so many different colors, patterns, and forms that it is unwise to generalize about their appearance. Many, however, have large, globular blooms, a dark signal spot below the beard, and intricate veining.

'New Vision' (Tasco, 2012). Note the large dark signal and globular form. (Photo: Superstition Iris Gardens)

'Navajo Velvet' (McAllister, 2009).

'Oyez' (White, 1938). Note the intricate veining.

Arilbred irises grow extremely well in the western US and similar climates. They prefer conditions that are on the dry side during the heat of summer and the cold of winter, although they are not desert plants and will thrive on ample irrigation during the spring and autumn. In the desert southwest of the US, arilbreds often perform better than tall bearded irises, growing more rapidly and blooming more reliably. Growers in wetter climates, such as the eastern US, often find them more challenging to grow, although many are successful with them nonetheless. If you live in a wetter area, I recommend giving your arilbreds a particularly sunny spot with good air circulation and good drainage.

'Parable' (Johnson, 2011). (Photo: Mid-America Garden)

'Eyes on You' (Black, 2012). (Photo: Mid-America Garden)

'Refiner's Fire' (McGrath, 2007). (Photo: Pete McGrath)

'Aladdin's Gem' (Thoolen, 2002). One of the smallest arilbreds.

Arilbreds come in all sizes, from tall-bearded size to dwarfs only a few inches high. This is because all different types of bearded irises (tall, median, and dwarf) have been used to breed them, and also because the aril species themselves come in a wide range of sizes. Most arilbreds bloom earlier than the TBs, overlapping the standard dwarf bearded (SDB) and intermediate bearded (IB) bloom seasons. They do not have the branching and bud count seen on TBs: a single short branch and 3 to 4 buds is typical of many arilbreds. They make up for it with individual flowers that are showy and spectacular, and by often producing many stalks, even on a young clump.

Have you tried arilbred irises in your garden? How do they like your climate?