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...

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?

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?

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'

The Evolution of Irises

by Tom Waters

Have you ever wondered where irises come from? Well, we all know they come in a box from Oregon via UPS. But I mean a little farther back than that. How did these particular plants evolve? How do they fit into the long history of life on Earth? How did they come to have so many shapes, colors, and sizes, and spread to so many different continents and climates? Iris is a wonderfully diverse genus, with between 200 and 300 species. And it is part of a larger iris family (which botanists call Iridaceae) that includes something like 2000 species, including other familiar garden plants like the crocus and gladiolus. Early botanists tried to deduce the family trees and family history of plants by noting their physical similarities and what clues could be gleaned from fossils. In this century, much has been learned from DNA studies, giving us a more complete picture of plant evolution. Peter Goldblatt of the Missouri Botanical Garden has taken a special interest in the Iris family, and Carol Wilson of Rancho Santa Ana Botanical Garden has studied the genus Iris itself in more detail. I’ve relied heavily on their work in putting together this post.

Origin of the Iris Family. Like many families of flowering plants, the iris family has its beginnings in the late Cretaceous period. At that time, the Earth’s climate was about 8C (15F) warmer than today, and there were no polar ice caps. Sea levels were high, and many areas were covered by shallow inland seas. It was a time when flowering plants were spreading throughout the world. They were diversifying and evolving rapidly, both encouraging and encouraged by the simultaneous evolution of bees and other insect pollinators. The iris family probably got its start about 82 million years ago, in what is now Antarctica.

Antarctica?

At that time, Antarctica wasn’t centered on the South Pole, but was nearer Africa, with some parts of it extending well north of the Antarctic Circle. It was still joined to Australia on the east. The climate was temperate, although cool, and the high latitude made for long summer days and long winter nights. It is thought that the strappy, vertical leaves (a distinguishing feature of the iris family) evolved to make maximum use of the sunlight, which would have been nearly horizontal much of the time. Two of the earliest branches of the iris family were isolated in Australia as it broke off from Antarctica, and five others developed in Madagascar and South Africa. (Madagascar and India were wedged between Antarctica and Africa in the southwest Indian Ocean at the time, making it possible for plants to migrate between the two continents.)

Around the time these different branches of the iris family were evolving away from one another and beginning to develop their own separate identities, the Earth experienced one of its great mass extinctions when a meteorite struck the Earth in what is now the Gulf of Mexico, 66 million years ago. Most people think of this event in connection with the extinction of the dinosaurs, but its effects were much more far-reaching than that. Many species of plants that depended on photosynthesis were driven to extinction by the dark envelope of dust that shrouded the Earth following the impact. 

Fortunately for the iris family, Antarctica, Australia, and South Africa—on the opposite side of the globe—were the best place to be. Although it is estimated that more than half of North America’s land plant species were lost in the extinction, few if any species were lost “down under,” although the numbers of individual plants plummeted.

With Antarctica moving south and the world growing colder, the future of the iris family now belonged to these plants that had colonized Africa and other warmer lands.

Two of the types of early irids (members of the iris family) in south Africa turned out to be very successful, spreading to other parts of the globe. These are also the branches of the family most familiar to gardeners today: iridoids and crocoids.

Iridoids and Crocoids. No, they are not rival alien factions from Dr. Who. The iridoids are members of the iris family related to irises, and the crocoids are members of the iris family related to crocuses. The iridoids include irises, as well as other familiar genera like Tigridia, Sisyrinchium, Moraea, and Dietes. A prominent distinguishing feature of the iridoids is their wide, arching, petal-like styles that cover the anthers and end in a crest. We can picture this emerging as an especially effective way to channel bees into the heart of the flower. The crocoids include crocuses of course, but also Romulea, Ixia, Tritonia, Freesia, Crocosmia, and Gladiolus. It’s hard to imagine a stylish modern garden without at least of few of this crew. Crocus, Romulea, and Gladiolus eventually found their way north into Eurasia from their south African origins, but it was the iridoids that eventually made it all the way to the Americas.

Iris. In the iridoid clan, the closest relatives to the irises themselves are the South African Moraea, Dietes, and related genera. Iris separated from these genera about 45 million years ago. The great sea that had divided Africa from Asia was gradually narrowing and vanishing, perhaps allowing the ancestors of the irises to find a new home in Eurasia. Later, the Sahara and Arabian deserts would prevent their return south.

Turkey seems to be the center from which the genus Iris has spread throughout the northern hemisphere. Many different types of irises are found in Turkey today, whereas most other regions have just a few local species.

For centuries, botanists had assumed that the most fundamental divisions of the genus could be seen in the different rootstocks: Junos with their bulbs and fleshy roots, xiphiums (which include the Dutch irises so popular with florists) with their tulip-like bulbs, the small reticulatas with their bulbs covered in netting, and of course those that grow from rhizomes. Some botanists even put these groups into different genera based on their rootstock. The rhizomatous branch of the genus was presumed to have then split into beardless, crested, and bearded sorts.

Iris unguicularis 'Lavender Moonbeams' (Tasco, 2014):
the newest version of the oldest iris?
photo: Superstition Iris Gardens

What has become clear recently is that these different rootstocks do not represent an early division of the genus into separate branches. Early irises were probably all beardless and all grew from rhizomes. These evolved into several different branches still having these basic characteristics, and then some of these branches gave rise to offshoots with deciduous foliage and bulbs as an adaptation to climates with very dry summers. So spuria irises are more closely related to Dutch irises than they are to Siberians, for example. Crested irises arose in more than one branch of the family tree, and are not a precursor to the development of beards. The earliest group to branch off from the others is represented today by Iris unguicularis and the closely related Iris lazica. If you want to have a mental picture of what the ancestor of all irises was like, Iris unguicularis is a good candidate.

Next, the family tree split into two branches, one of which spread mostly westward in the vicinity of the Mediterranean, while the other spread mainly northward and then east into northeast Asia and eventually North America. The Mediterranean branch produced the bearded, oncocyclus, and Regelia irises, but also gave rise to the Junos, and apparently the crested irises of east Asia, such as Iris japonica  and Iris wattii. These are actually more closely related to the Junos (which also often sport crests of various sorts) than to any other groups. Interestingly, one small branch of this group gave rise to both Iris dichotoma and Iris domestica, once thought to be so dissimilar that they were each placed in their own genus!

Meanwhile, the Asian branch of the genus led to the spurias, xiphiums, and reticulatas, plus most other beardless species. The migration of irises into North America was apparently not a single event, as there is no single branch of the iris family tree that has all the American irises and no Asian iris. The American crested irises, including Iris cristata, have the oldest lineage, but they do not seem closely related to the east Asian crested irises, as was once supposed. The crest feature developed independently in these two distantly related branches. A second venerable branch of irises in north America includes Iris missouriensis (the Rocky Mountain Iris), and the western species Iris tenuis. The Louisiana irises represent another early branch of the evolutionary tree. The other North American irises were presumably later arrivals, with close cousins in Asia. Iris virginica is related to the Siberian Irises and to Iris pseudacorus; this Asian-American grouping has a common ancestor with both the Pacific Coast group and also with the widespread Asian Iris lactea.  

Bearded Irises. The bearded irises grow around the Mediterranean, with some species ranging northward into central Europe. The tall bearded irises were the first to attract the attention of European nurserymen and plant breeders in recent centuries, and they are the most represented in our gardens today. There was probably an earlier division of bearded irises into dwarf species with a basic chromosome count of 8 (Iris attica, Iris pseudopumila, and Iris pumila, which apparently arose as a tetraploid hybrid of the first two) and other species (mostly taller and branched) with a basic chromosome count of 12. It is from this latter branch that our modern TBs, BBs, and MTBs are directly derived. The chart of bearded iris relationships here is not from DNA studies, but based on chromosome analyses, geographical considerations, and other suppositions.

In the big picture over long time scales, we think of evolution as a branching tree, where populations divide, become isolated, and go their separate ways to form new species. But if we look at the process in more detail, we see that species sometimes come about in other ways: as hybrids of earlier species, by polyploidy (doubling or otherwise increasing the number of chromosome sets), or by both these processes at once. The relationships among the bearded irises, for example, sometimes resemble a branching tree, but in some instances are more like a network, which species separating and then coming back together to make new species. Evolution is an intricate process.

Irises, being prized as garden flowers, have attracted the attention of human breeders. When looking at the difference between modern hybrid TBs and their wild predecessors, it is tempting to see a new, accelerated evolution now dominated by human intervention. But although the effects of human breeding efforts are dramatic, it remains to be seen what impact they will have in the long term. Our own genus Homo is perhaps 3 million years old; the genus Iris has been here about fifteen times as long already. The last two centuries of iris breeding, compared with the 45-million-year evolution of the genus, is a very tiny fraction indeed (the same as about half a second out of a day). The irises humans have created mostly depend on humans for their existence—you find them in gardens, and sometimes in old cemeteries, but they have yet to take over the Asian Steppes or the Amazon. Will there still be irises 5 million years from now? 20 million years from now? Will our present interest in them leave any traces that far in the future? 

Plate tectonic maps by C. R. Scotese, PALEOMAP Project (www.scotese.com). Used with permission.

Understanding Iris Descriptions

by Tom Waters

If you've spent some time looking for information about particular irises, you've probably encountered something like this, which I've copied from the American Iris Society (AIS) online Iris Encyclopedia:

'Montmartre' ( Keith Keppel, R. 2007). Seedling 01-49B. TB, 33" (84 cm), Early thru midseason bloom. Standards greyed red-purple (M&P 45-J-5), 1/4" straw yellow (10-F-2) edge; style arms straw to reed yellow (10-I-1), midrib flushed red purple; Falls velvety dark red purple, darker and brighter than raisin purple (54-B-12), narrow oyster white (10-B-1) edge, inner haft lemon (9-L-2), white around beard; beards chrome yellow (9-L-7), white and lemon at end. 99-61A: (96-11D, sibling to 'Moonlit Water' x 'New Leaf') X 'High Master'. Keppel 2008. Honorable Mention 2010, Award of Merit 2012, Wister Medal 2014.

Most of this text is from the official description of the variety as published by the AIS. The information is presented in a standardized order and format. Even unofficial descriptions, as you might find in catalogs or other publications, tend to follow this format to some extent, although usually somewhat simplified.

This is a rather intimidating mass of text for the novice iris enthusiast to process. In this post, I will step through it all one piece at a time, explaining what it all means and sharing some interesting background information along the way.

The first portion is this: "'Montmartre' ( Keith Keppel, R. 2007)." 'Montmartre' is the name of the iris; Keith Keppel is the person who created it, and 2007 is the year it was registered ("R.") with the AIS.

Registration is the process by which a new iris is assigned a unique name. Why is this necessary? Can't the person who breeds a new iris just call it whatever he or she feels like? That was essentially the state of affairs in the nineteenth century, when nursery businesses devoted to ornamental plants were coming into their own. The result was a great deal of confusion. Different plants were being sold under the same name, and some plants were being sold under more than one name. Furthermore, plants were sometimes given names that looked like botanical names but were not. The bring order out of chaos, an international system for naming cultivated plants was created. This is the International Code of Nomenclature for Cultivated Plants (ICNCP). The code includes rules about what form a name may take (it can't look like a botanical species name, for example, cannot be excessively long, or be just a descriptive word like "yellow"). For many types of ornamental plants, the ICNCP rules are implemented through a designated International Cultivar Registration Authority. For all irises except those that grow from bulbs, the registration authority is the AIS. So it is the role of the AIS to ensure that new irises are named according to the rules, and that each name is officially assigned to a single particular cultivar.

(The world "cultivar", coined from the phrase "cultivated variety", is the technically correct term for a unique plant. Although the term "variety" is often used, that word has a different meaning to botanists.)

Cultivar names are enclosed in single quotes, according to the ICNCP. There was an older practice of printing iris cultivar names in capitals, which you may still encounter from time to time.

So 'Montmartre' was registered with the AIS by Keith Keppel, the hybridizer who created it, in 2007. The person who registers an iris is usually the hybridizer who made the cross that produced it, but this is not always the case. One can register a particular or distinctive form of an iris species found in the wild or raised from collected seed with no deliberate cross-pollination involved. In this case, the person who registers the cultivar is just the person who has grown the plant and decided it should be named. It also sometimes happens that one person selects the plant to be registered, even though the cross that produced it was made by someone else. For example, 'Brown Lasso' resulted from a cross made by Gene Buckles, whose seedlings were passed on to David Niswonger when he died. So it was Niswonger who registered 'Brown Lasso' on behalf of the deceased hybridizer. The registration for this iris reads as follows:

'Brown Lasso' ( Eugene Buckles by David Niswonger, selector. R. 1972).

There is no requirement that the person who made the original cross be acknowledged in this fashion, but it is a commonly observed courtesy. 

It also sometimes happens that an iris has been in circulation for many years, without ever being registered, and an iris society or knowledgeable individual may step in and register it, so that its name can be officially recorded with a proper description.

I sometimes encounter people who are under the impression that registration somehow implies that the iris is deemed worthy by the AIS, or "approved" to be sold. This is not the case. The AIS does not make any judgment on the merits of the cultivars that are registered. The sole purpose of registration is simply to officially assign a name to a cultivar.

The next part of the description of 'Montmartre' is

Seedling 01-49B. TB, 33" (84 cm), Early thru midseason bloom.

First comes the hybridizer's seedling number. Hybridizers usually raise so many seedlings that they use numbers to keep track of them until a few are selected to be named. There is no standard format for numbering seedlings; each hybridizer has his or her own system. Why is this number included in the official description? It seems superfluous once a name has been chosen. One reason is that the iris may have been used for breeding, and referred to by number in a pedigree, before being registered. It also helps people in the future interpret the hybridizer's breeding records. Furthermore, the iris may have been grown and seen under its seedling number, for example at an iris convention, and this lets everyone know that this new iris is the same one they admired (or detested) when they saw it earlier.

TB stands for "tall bearded". Each class of iris has its own abbreviation. Next follows the height in inches and centimeters. The height of an iris can vary considerably, even in one garden, and much more so if grown in different climates and soils. So the height figure is best taken with a grain of salt.

Next comes the season of bloom ("Early through midseason"). You may also see the bloom season expressed in abbreviations: E-M, in this example. Bloom season is not referred to calendar dates, because that changes enormously from one climate to another, and even from year to year. Rather, it is expressed relative to other irises of the same type. So in this case, we know that 'Montmartre' starts blooming somewhat earlier than most TBs and continues blooming into the middle of TB season. These designations are always relative to the type of iris involved, so a standard dwarf bearded (SDB) iris with midseason bloom means it blooms in the middle of SDB season, even though this may be a month or so before TBs bloom.

Next comes the color description, which is often the longest part. The standards (upper petals) are described first, followed by the falls (lower petals, which technically are sepals). In this particular description, you will notice alphanumeric codes being used to describe the colors. There are a number of different color charts published by various individuals and organizations to help identify colors more precisely than common language can do. In this case, the system being used is that of Maerz and Paul (note the "M&P" given the first time a code appears in the description). Other color systems often encountered are RHS (Royal Horticultural Society) and Ridgeway. If you have access to the specified published color chart, you can consult it to see precisely which colors are referred to in the description. There is an important caveat, though: colors can vary depending on soil and weather and the age of the bloom. So the precision implied by using a color chart is somewhat illusory.

The M&P color system used in this description also assigns English names to colors, and these are used in the description ("reed yellow", "raisin purple", and so on). These sometimes strike me as rather too fanciful to be useful without consulting the color chart, but they can convey some general distinctions. (I think we all have a sense of how straw yellow differs from lemon yellow, for example).

One is not required to use a published color chart when describing an iris, and many hybridizers do not. In recent years, the AIS has been collecting photographs along with the registration descriptions, which is a wonderful development. A picture is indeed worth a thousand words. A photograph is not required, however, just encouraged.

At the end of the description comes the parentage, or pedigree, of the iris. The pod parent is given first, then a large X, then the pollen parent. These may be named cultivars, or seedlings identified by number, parentage, or both. The parentage can sometimes be dauntingly complex if the hybridizer has been using their own seedlings for many generations.

Let's untangle this particular parentage, which is fairly easy as such things go. First look for the large X that separates the two parents. We can see right away that the pollen parent is 'High Master'. What about the pod parent? It is this:

99-61A: (96-11D, sibling to 'Moonlit Water' x 'New Leaf')

The pod parent is a seedling numbered 99-61A. (Since no other hybridizer is indicated, this is one of Keith Keppel's own seedlings.) That seedling's parentage is given inside the parentheses, after the colon. Its pollen parent is 'New Leaf' and its pod parent is another seedling, 96-11D, which we are told is a sibling to 'Moonlit Water'. So if we want to know that seedling's parentage, we can look in the description of 'Moonlit Water' (siblings have the same parentage, by definition.) Why refer to it that way? Why not just give its parentage? In this case, it is an enormous space saver. Look up the parentage of 'Moonlit Water' and you'll see what I mean!

Sometimes you will see a description that says "parentage unknown", or lists a pollen parent as unknown. When the pollen parent is unknown, it could be that the cross was made by insects, rather than the hybridizer. (These are often referred to as "bee pods".) This is not always the case, however. Particularly when the entire parentage is unknown, it is likely to be a case of an intentional cross with lost of confused records.

Following the parentage, we see "Keppel 2008". What is this? We already saw at the beginning that the iris was registered by Keppel in 2007. This last bit of information is the record of introduction. "Introduction" is short for "introduced into commerce" and refers to when and by whom the iris was first offered for sale to the public. In this case, Keith Keppel sells his irises himself, so we just see his name and the year 2008. It is rather common for an iris to be registered in one year and first offered for sale in the following year, although the gap can be longer, or an iris can be introduced the same year it is registered. If the iris were introduced by a commercial garden, it is the name of the garden that is used. For example, Mid-America Garden introduces irises bred by Paul Black and Thomas Johnson.

Why is introduction important? One reason is that where and when an iris is introduced determines its eligibility for AIS awards. (AIS awards are given only to cultivars introduced in North America, and the year of introduction determines when an iris becomes eligible for awards. The AIS does not recognize an iris as having been introduced until the person who registered it sends evidence of introduction to the registrar.

In fact, the year of introduction is so important that when an iris is referred to in text, the hybridizer and year of introduction are often given in parentheses following the name: 'Montmartre' (Keppel, 2008).

Can an iris be registered and not introduced? Indeed. Registration, remember, is just the official assignment of the name to the plant; it does not imply anything about whether the iris should or will be offered for sale. The hybridizer might lose the plant, decide not to sell it, or be unable to sell it for some reason.

Conversely, there are irises (mostly older ones) that have been introduced into commerce but never registered. The ICNCP is not a legally binding set of rules, nor does the AIS have any legal standing to require irises to be registered before they are sold (although an iris must be properly registered to be eligible for AIS awards). So there have been iris hybridizers (mostly in past eras, and mostly working outside the US) who did not bother with registering their creations before selling them.

Finally, at the very end, is a list of the awards the iris has received: in this case, Honorable Mention, Award of Merit, and the Wister Medal.

I hope this post has given some insight into the nuances and complexities of iris descriptions. If you have any questions, please ask in the comments below, and I will do my best to answer!

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?

Growing Irises Organically

by Tom Waters

Today, I thought I'd write about organic gardening methods, particularly my experiences of them as an avid iris grower. When I first took up growing irises in the 1970s, organic gardening was still very much a fringe movement. Storage sheds full of bags of synthetic chemicals intended to address every conceivable gardening problem were the norm.

Today, organic gardening has become mainstream. Most modern gardening books emphasize organic practices, and many people are excited about having gardens that resemble nature and use nature's own cycles and processes. This post is not meant to be polemical. Rather, I'm just hoping to provide some starting-off points for people interested in using more organic methods in their own gardens.

Fertilizer

When I began transitioning to organic gardening methods in the 1990s, I was relatively unconcerned about synthetic fertilizers. A fertilizer is not a poison after all. And what difference does it make if the nitrogen a plant needs comes from a factory or from a compost pile? Nitrogen is nitrogen, after all. But a lot has been learned about the negative effects of synthetic fertilizers in recent decades. The processes used to synthesize nitrogen and phosphorous fertilizers depend on petroleum, and so are not sustainable and contribute to greenhouse gases in the atmosphere. Furthermore, fertilizer runoff has created an enormous problem: eutrophication of our lakes and waterways, causing ecosystem destruction on a huge scale. Granted, home gardeners are not the main culprits in this problem, but why should we be adding to it if we don't need to?

despite rumors to the contrary, irises do grow and bloom
without the use of synthetic fertilizers

Beyond all these considerations, our understanding of soils has progressed tremendously since the mid-20th century. A healthy soil is an ecosystem unto itself, harboring extraordinary numbers of decomposers, from earthworms and beetles down to micro-organisms and fungi. All these creatures process waste matter into nutrients that plants can use, creating a self-renewing reservoir of the ingredients plants need to thrive. A blast of highly soluble nitrogen or phosphorus from synthetic fertilizer can completely disrupt the chemical environment in which the soil organisms live. The instant "boost" the irises get from the synthetic fertilizer comes at the expense of destabilizing the soil ecosystem over the long term.

Consider doing nothing. Beginning iris growers are often told something like "fertilize with superphosphate or a low-nitrogen fertilizer such as 5-10-10 before bloom in spring and again in fall." So common is this mantra, that people often do not even step back to consider why fertilizing is necessary at all. There have been flowering plants thriving on the Earth for the last 160 million years or so, and petrochemical-based fertilizers have only been around for about a century. So obviously they are not needed - in the big picture of things, at least. Irises will grow and bloom almost anywhere their water and sunlight needs are met. My advice to beginning growers is to not worry about fertilizers unless your plants appear unhealthy. And then, have a soil test so that you know what exactly is deficient. Then, look for organic methods to supply the deficient nutrients.

The virtues of compost. Compost is the single most important thing you can do for your soil. If improves soil texture, helping to capture air and water which plant roots need. And it feeds all the decomposers and other organisms that make for a healthy soil ecosystem. Even better, it does all this almost irrespective of what type of soil you are starting with. Everyone should have a compost pile. But remember its main virtue is as a soil amendment; it must be added in volume to make much of a difference. Composting your kitchen scraps is not going to produce enough compost for a whole garden. You can buy compost from commercial sources. You can also collect leaves and other vegetation waste to compost. Animal manure is also an excellent compost ingredient.

There are various other organic products intended to provide specific nutrients, such as cottonseed meal, alfalfa meal, bone meal, blood meal, and so on. These provide organic alternatives to some of the synthetic fertilizers. But as with synthetics, it makes sense to do your homework and learn if the specific deficiencies these products address really apply in your case.

A final thought: A boost of synthetic fertilizer can indeed create visible effects quickly. You might get taller stalks and larger flowers, for example. Putting synthetic nitrogen on your lawn can make it look noticeably darker and greener a week later. But these effects do not mean that the synthetic fertilizer is improving the overall health of your irises, or your lawn. Health requires more of a focus on the long term.

Weeds

weed or wildflower?

One well-known herbicide is the focus of controversy everywhere you look these days. I don't intend to engage that particular debate here, as it would quickly take on a life of its own and distract from the bigger picture of organic gardening practices, which is the subject of this post.

I find that weed control represents most of the labor involved in my garden. It's a huge task, much more laborious and time-consuming than watering, soil building, grooming, planting, dividing, and all the rest. I think most gardeners' experience is comparable, wherever they live.

Consider doing nothing. That sounds ridiculous, but let me explain There's two parts to this suggestion.

(1) Consider not using any herbicides at all. I remove weeds from my iris beds mechanically (pull them out). This is really the only way that is 100% safe for the irises and other desirable plants in the garden. And although it is a lot of work, it does have the bonus of keeping you familiar with how every square inch of your garden is doing. I couldn't do it without my handy padded kneeler, but at present I can more or less manage. Having said that, I do understand that there are many people who would have to give up gardening entirely if hand-weeding were the only option.

(2) Consider what needs to be removed, and what doesn't. In recent years, I've become very interested in native plants, and it has changed my philosophy of gardening. Certainly, there are some plants that will absolutely overrun a garden if left unchecked. But there are others that are really only a problem in the eye of the gardener. Originally, I ruthlessly pulled everything I didn't plant. Now, I know all the regular interlopers individually, and I pull things that I specifically know to be problem species. Some other natives (and self-sown garden plants) get to stay if they are in a place where they will not cause serious harm, Native plants in the garden help "tie it in" to the surrounding landscape, and provide benefits for local wildlife. They are also inherently adapted to the environment, reducing water needs and other types of care for the garden as a whole.

Understand what you use. If you do decide to go the herbicide route, there are certain questions you need to answer in making your selection. This is just as true for organic or "natural" herbicides as for others. (1) What does it do? Does it just kill top growth, or does it get the roots of perennial weeds? (2) How harmful is it for humans, pets, or wildlife? (3) Does it damage the soil? Some popular "recipes" for making herbicides out of household products circulate on the internet. Just because you can find something in your pantry doesn't mean it's "harmless" in the garden. Do the research.

This year, I've been using a commercial product that is a mix of highly concentrated vinegar, orange oil, and molasses. It's very satisfying to use, as it burns off top growth almost instantly. It does have limitations, though: it really needs sunlight to act fully, and it only kills the leaf surface that it actually lands on. This means the to completely kill a plant, you need to apply a lot of it. And of course, it has no effect on roots. I have extremely alkaline soil, so I'm not worried about the effects of the acid - that might be different if I lived where soil was too acid to begin with. It's useful stuff, but not suitable for all jobs.

Pests

The dangers of chemical insecticides have for decades given great impetus to the organic gardening movement. Things presumed safe by one generation of gardeners are later understood to be dangerous and taken off the market.  It's not surprising that some people just want to stay clear of all of them.

Today, people are also just more aware of the shortsightedness of introducing poisons into the environment we share with other plants and animals, even if there are no direct consequences for us humans.

But most every gardener at some point or other has experienced an insect infestation that has gone completely out of control.

'Dollop of Cream' with chives

Consider doing nothing. It's not necessary to react to every insect sighting or every sign that something has been nibbling on a leaf or two. In most places, in most years, there is an ebb and flow between pests and their predators; nature can be wonderfully self-correcting. Garden planning is an important too, as well. Pests tend to exploit monocultures. The more different kinds of plants you grow, the less likely you garden is to become a beacon to one particular pest species. Some plants actively repel certain pests. Aphids don't like alliums, for example. I have not had the tiniest aphid issue since I studded my garden with clumps of chives.

Now this has gone too far! Sometimes, though, doing nothing is not an option. Organic controls fall into two broad groups: predators (ladybugs, for example) or species-specific parasites/diseases. As I write this, I am in the midst of grasshopper infestation of Biblical proportions. All 150 iris seedlings I lined out this spring were killed in a matter of days. A friend recommended Nolo bait, a parasite that eventually spreads through the grasshopper population. It's not instantaneous, but works gradually over months, sometimes requiring further application the second year.

local fauna or evil incarnate?

A little research on the internet will turn up a range of organic solutions to most gardening problems. One of the things we give up when going organic however, is instant gratification. Organic methods are not about the quick fix, but about putting things in place now that will reduce problems in the future.

I know that for some people, the choice to use or not use organic gardening methods has a political dimension. For myself, I am more motivated by a passion for the natural world, the great diversity of life, and a love of growing things. When I use organic methods, I feel like I'm learning how nature works and gardening with nature, participating in the great web of life rather than battling with it.

Do you use organic methods in your garden?