It’s mid-May and my iris have been in bloom and looking magnificent. Not just a few or even a few dozen but several hundred of them, so as you can probably tell from the sheer number I grow, they’re one of my favourite plants. And it’s not just me.

While the American Iris Society’s claim that the Iris is “the Greatest Show in the Floral Kingdom” might be a bit of an exaggeration, it’s not far off because Iris have long captured the human imagination, and today there are many specialist iris nurseries, societies and websites including several specialising in historic varieties.

As usual the photos are mine unless otherwise acknowledged

Iris can be seen in the botanical garden of Thutmosis III at Karnak and in frescoes in Minoan Crete, while it was the great ancient Greek botanist Theophrastus who first named them after Iris, Juno’s messenger and the rainbow goddess because whenever she landed on the earth beautiful flowers sprang up.  Artists ever since have fallen for them and they have been imbued with symbolic overtones, both religious and secular.

I had originally planned to write another post about iris in art but have been beaten to it by Lucy Ellis’s very readable account “The iconic iris: a floral favourite in art” on ArtUK which I’d recommend as a good introduction to the subject.

Iris are a genus of the wider Iridacaeae family, alongside gladiolus, crocus and freesias amongst many others.  They grow all over the temperate parts of the northern hemisphere in an extraordinary wide range of habitats from the waterside and bogs to high mountainous areas and deserts.  It is also, after the rose family, the most complex group of plants  in terms of genetics.   There are approximately 260-300 members of the genus, all herbaceous or semi-evergreen, although some have bulbs, while others have rhizomes.

It’s not really surprising that Theophrastus named them after  the goddess of the rainbow for they come in virtually every colour except true red.

But while the range of colours is as broad as the range of their habitats,  the shape and structure of Iris flowers is remarkably similar across the whole family.

True petals or standards in the middle surrounded by sepals which face out or down but  which are known in iris terminology as falls.

 

Perhaps what might be surprising, however, is that almost none of the species iris are grown in our gardens. Instead what we grow are almost all hybrids or selections from species. As Sandra Knapp of the Natural History Museum says in her wonderful book, Potted Histories [2003]   “Nature has done a great deal with the iris, helped and hindered by humans over the centuries. The cultivated iris is a prime example of how the common names of plants can be fantastically out of step with the reality of their origins.”  This has led to most cultivated iris having a very complicated taxonomy, so complicated that I’m not even going to attempt it.

If however you do want to know more about the taxonomy of Iris then  see Brian Mathew, The Iris 1981, and if you want to see how complicated it can be, see this scientific article: “Phenotypic Variations and Heritability in Hybrid Populations of Bearded Iris”, in Hort Science 2019.

I don’t have the knowledge or the space here to talk about the whole Iris tribe but instead I’m going to concentrate on the one that most of us are probably thinking about when iris is mentioned: the flag iris which gets its other common name – the bearded iris -from the fact that in some species there are tufts on the innermost part of the falls – usually in a contrasting colour – which resemble beards.  You’ll often see them in garden centres or nursery catalogues described as Iris germanica. This is the name given to them in 1753 by Linnaeus because of where he thought they came from originally. It was he too who divided the 18 species of Iris he knew into  two groups – the Bearded  and the Beardless – a basic classification that is still used today. Today  bearded iris  are further classified by height – in six groups from miniature dwarf to tall, which interestingly also  flower in the same order, between early spring to June.

In fact it’s now thought that Iris germanica  isn’t a “wild” plant but a very ancient wild hybrid. Its parents are thought to be Iris  pallida, which is 60-90cm tall, blue/purple from the Italian and Austrian mountains down to the Adriatic, and Iris variegata, from Hungary and the northern Balkans, which is much shorter and yellow/brown,  although there may be other species involved somewhere back in prehistory too.

If you grow them you’ll know that flag iris are extraordinarily tough, cope well with cold winters and baking hot summers, poor soil and they tolerate drought.  I’ve even seen them  in Normandy  growing on the ridge of cottages with thatched roofs. [For more on how that’s possible follow this link]  If the drainage is OK they’ll even cope with excessive rainfall.  In other words  they are almost impossible to kill, perhaps because they have what John Grimshaw in The Gardener’s Atlas, calls “hybrid vigour”.   However although they are incredibly resilient they have not become an invasive species because while the rhizomes grow and bulk up  relatively rapidly they only spread at a snail like pace, with clumps tending to become congested rather than invading neighbouring ground.

By the late 16thc Clusius was able to describe 28 varieties of bearded iris, probably all seed grown, and he knew from experience that Iris grown this way “vary in a wonderful way.”  Their wide variety was also noted by Gerard who wrote in  his Herbal of 1597 that “there be many kinds of Iris or Flouer-de-Luce, whereof some are tall and great and some little, small and low. Some smell exceeding sweet in the roote, some have not any smell at all; some flowers are without any smell and some with; some have one color, some have many colors mixed; Vertues attributed to some, others not remembered; some have tuberous or knobbie rootes, others bulbus or onion rootes; some have leaves like flags, others like grass and rushes.”

With such variability in seed grown plants hybridisation didn’t really get under way until the first decades of the 19thc when Marie-Gillaume [sometimes known as Paul] de Bure, a wealthy Parisian plant enthusiast, began work improving a seed raised strain, the first of which  was introduced into commerce in 1822 as “Buriensis”.  He wrote up his research in  the Annales de Flore et de Pomone in 1836.  and in the Journal of the French Royal Horticultural Society in 1837. “Buriensis” was  still available commercially  in 1920, altho I understand it has now been lost and I can’t find an image of it anywhere.

De Bure’s efforts inspired another French gardener Henri-Antoine Jacques, gardener to the future King Louis Philippe and  famous for his introduction of the Bourbon rose and for hybridising roses. Jacques now began to hybridise iris too, and although most of his introductions were soon surpassed by better varieties he did manage to breed the outstanding yellow  iris of the time known as  “Aurea”.

In his turn he inspired yet another French grower Jean-Nicolas Lémon who had a nursery on the outskirts of Paris. Lémon began to specialise in  Iris and by 1840 had a catalogue of around 100 cultivars, with more new ones introduced  each season for the next 15 years.  At least a dozen of his introductions   are still available today,  amongst them are “Madame Chereau” which became one of the most popular varieties in the later 19thc  and “Jacquesiana” named after his mentor. [There is a history of “Jacquesiana” at the Heritage Iris website.

Lémon’s work led to a wave of other nurserymen all across western Europe getting in on the act through the mid and later 19thc. Amongst them were John Salter, who had had a nursery at Versailles in France before moving back to England and opening his  Versailles nursery in Hammersmith. He bought back French varieties and took them into commercial cultivation and also started making his own crosses.  

[Andrew King of the British Iris Society is collecting Salter’s introductions so if you have any more information I’m sure he’d like to hear from you.]

Another was  Peter Barr who is better known for his work on daffodils and who I have written about previously.  Barr also imported many of these French cultivars to Britain, and  used them in his own iris breeding programme.  This resulted in several dozen new cultivars, with his catalogue offering a range of over a hundred, alongside selling iris seed as well.  Barr’s catalogues were widely circulated, including to the USA, where, as we will see shortly, it led to a huge rise in interest in growing iris.

Salter and Barr were not alone. Barr’s neighbour in Tooting, Robert Parker, [who we encountered in an earlier post about Benjamin Williams] and  Thomas Ware a Tottenham nurseryman also began breeding programmes, and I’ve already written about William Caparne, the artist turned iris breeder on Guernsey.

It soon meant that  there so many new named Iris cultivars that they needed a system of classification. Peter Barr seems to have been fairly obsessive about classifying plants so, as he did with  daffodils he suggested a way of classifying iris into groups which he spelled out in The Florist and Pomologist in 1884.  It became the generally accepted system until the 1920s.    By this time however many people thought that further improvement was virtually impossible because the natural limits of flower shape, size, height and colour must have been reached. How wrong can one be?  It just required “new blood”.

Sir Michael Foster, a keen gardener who also happened to be the  professor of physiology at Cambridge and secretary of the Royal Society was the man who introduced it, although that would be pretty difficult to guess from his entry in the ODNB which is almost entirely about his medical and political life merely adding “He was a knowledgeable horticulturist who specialised in irises. He created many new hybrids and occasionally published articles in gardening and horticultural journals.”

You can see from his extensive writing about iris  – there’s a full list of his articles here  – that he was mainly interested in  the bulbous sorts rather than flag iris or  “So-called German Iris” nevertheless he wrote about them at length  in The Garden, p.508 November 14, 1885.    Foster knew that iris  cross-pollinated easily so began to look for new species to introduce to the gene pool. The breakthrough came when he asked a group of missionaries in Turkey to send him local  irises.  Of course they weren’t botanists and sent him seeds/plants without labels identified only by the names of the places where they had been found. Even today no-one is quite sure of all of them, although the most important was from the area around Amasyia in Anatolia.   Introducing them into his breeding programme  enabled Foster  to transform bearded irises within a comparatively short space of time.

This was because, to be a bit technical,  iris germanica, like  most plants, is  diploid ie it has two sets of chromosomes in each cell, whereas the Turkish iris that Foster had been sent and then used in his experiments had  4 sets ie are tetraploid.  That means there is a much bigger  range of potential variations.

Lucy Skellorn, Sir Michael’s great-great -granddaughter, who is based  in Suffolk, is the  National Collection holder of the irises he introduced, and she runs an informative website about the collection and his work.

Foster died in 1907 but his work was continued by some of his friends.  One was William Rickatson Dykes, a master at Charterhouse who inherited Fosters garden records and notes. He decided to go and explore the European origins of Iris germanica, finding Iris pallida and Iris variegata and many naturally occurring hybrids between the two in the mountains north and east of the Adriatic.

Dykes continued travelling, documenting and recording iris species, and  his beautifully illustrated book The Genus Iris, written in memory of Foster, was published in 1913.  He introduced a further 34 cultivars before his death in a road accident  in 1925.  His widow introduced the Dykes Trophy for the most outstanding new variety and it remains the major award in the Iris world.

Dykes, like all true gardeners, started sharing his findings and plants and seeds to interested friends.  One of them was Arthur John Bliss, almost always known as A.J. who began his own iris breeding programme in 1902 keeping extremely careful records of all his crosses.

Helped by his niece Phyllis he introduced over 150 new cultivars  and although he never achieved his great aim of creating a crimson iris his efforts did result in a group which became very significant for later iris breeders.  It included the deep purple  Dominion which, when it was introduced into commerce, commanded 20 times the standard price for a rhizome.  It even has its own biography!  Since 2008 there’s been a  National Collection of Bliss Iris assembled near Cirencester by his great niece, Anne Milner  and there is an interesting website devoted to him and his iris which is well worth a look. 

While all that was going on in Europe things were also developing in America.  As I said earlier Peter Barr’s catalogue contained over 100 cultivars. The whole range was bought by Bertrand Farr, a keen gardener who owned a music shop in Philadelphia.

Farr who also bought extensively from the catalogues of other leading European nurserymen, including William Caparne who I’ve written about elsewhere. As these grew the results were enough to convince him to stop selling  and get growing!   He sold the music shop  and  opened his own nursery. 

Farr’s Hardy Plants  dominated the market for the first decades of the 20thc. By the time he died his iris catalogue stretched to over 1200 cultivars.  Farr’s work was to  lead in 1920 to the formation of the American Iris Society, which was followed just 2 years later  by the start of the British iris Society.  There’s more about Farr and his introductions  on the website of the American Iris Society, while a few of his catalogues are available via biodiversity Heritage Library.

The fact that Iris are easy to hybridise and the results can occasionally be spectacular, even  if most seedlings are merely “ordinary” has led to a lot of amateur interest over the last century. The American Iris Society’s website lists literally hundreds of amateur breeders so when I planned this post I thought I might do a series to look at some of the more famous ones, notably the artist Sir Cedric Morris, but very quickly I discovered that there is so much better researched and written information out there already that it was much more sensible to refer you to the best of it rather than copy and paste bits and pieces.   Suffice it to say that Morris and his house at Benton End in Suffolk  are now once again getting the interest they deserve.   The iris was his most prized plant, and every year he raised one thousand seedlings of his own crosses, breeding for subtlety of colour and perfection of form.  It’s thought he named about 90 of the best and  Sarah Cook, the former head gardener at Sissinghurst, has made it her retirement project to try and collect them all. Definitely worth finding out more!

Good places to try for further information on the Iris generally are : The American Iris Society, which has an excellent series of detailed articles on their history; The British Iris Society; The Historic Iris Preservation Society

For Morris, his iris and Benton End : The website of The Benton End House and Garden Trust ;  The Garden Museum website article on Sarah Cook’s search for Cedric Morris Irises;  Benton Irises, by Dan Pearson in Gardens Illustrated, May 2023;  “The Borders of Bohemia” by Olivia Laing, in World of Interiors, May 2023; there are photos of the known Benton Iris on the website of the Suffolk Group of Plant Heritage and Sarah Cook holds theNational Collection; and finally an interview with Sarah Cook on the website of the Historic Iris Preservation Society.  There is  also a YouTube video of Sarah Cook Talking at Holt Festival abut Cedric Morris and the Plants at Benton End.