Irises enjoy huge worldwide popularity. They offer gardeners an astonishing variety of eye-catching hybrids. These hybrids attest to an illustrious past and present with many expert plant breeders and specialist Iris societies across the globe. The nomenclature and taxonomy are complicated. The classification of Bearded Irises is particularly complex. Unfortunately, Linnaeus laid the foundations for this complexity by misnaming a hybrid as a species. Irises are known to complicate matters by hybridising in the wild. Plant breeding and improved genetic information complicates the Iris genus further.
Bearded Iris Terminology
Bearded Irises are a subgenus of the Iris genus. They are often referred to as Pogon Irises. Pogon (πώγων) is the Greek for beard. An Iris beard is generally described as looking like a furry caterpillar. See the annotated diagrams below for the key terminology used to describe Bearded Irises.
In addition to the beard, specialist terms to describe Bearded Iris flowers are standards and falls. The beard acts as a landing pad for pollinators. Standards are the 3 uppermost, upright petals of a Bearded Iris. Falls are the 3 lower petals that fall gently downwards. Iris-lovers enthuse about the contrasts in colour between the beard, standards and falls. Noted features are also veining, lines and dots. There is a completely separate and specialist Iris vocabulary to describe all these distinctions.
Iris and Bearded Iris Groups
Before venturing into subtle details, let’s look at the various groups of Irises and Bearded Irises recognised today. The British Iris Society website splits Irises into 6 sections with very clear photos demonstrating the plant variation at a glance: Bearded Irises, Siberian Irises, Iris reticulata, Dutch Iris, Iris pseudacorus and Iris laevigata. Bearded Irises are further split into the following size-related groups that are commonly described with standard acronyms:
- Miniature Dwarf Bearded (MDB)
- Standard Dwarf Bearded (SDB)
- Intermediate Bearded (IB)
- Border Bearded (BB)
- Miniature Tall Bearded (MTB)
- Tall Bearded (TB)
Specialist Standard and Fall Terms
Tall Bearded Irises are the cultivars that most readily spring to mind when we think of Bearded Irises. Their colourful glamour is so much sought-after that they have their own specialist vocabulary.
- Self: standards and falls are the same colour
- Plicata: stippled, dotted or stitched edges. Traditionally, these appeared on white or yellow. Breeders have extended the colour range to pink and apricot. Picotees have different colour edges to main flower.
- Amoena: coloured falls with white standards
- Variegata: yellow standards with red falls (also maroon or brown falls possible)
- Neglecta: pale blue standards with deeper blue falls
- Glaciata: pale-coloured standards and falls without any purple anthocyanin pigment
- Laminata: development of plicata with a more solid, darker colour and often with a halo around the beard
- Bitone: standards and falls of the same colour, but the standards are a lighter shade than the falls
- Reversed Bitone: standards and falls of the same colour, but the standards are a darker shade than the falls
- Bicolour: standards and falls of two different colours other than the colours specified in Amoena, Variegata or Neglecta above
- Broken Colour: standards and falls with splotches, blotches and streaks in random patterns
- Emma Cook Pattern: darker ring of colour around the edge of the falls
- Blend: a mixture of colours.
Linnegar and Hewitt advise that Bearded Irises are often incorrectly called Iris germanica L. in their RHS Wisley Handbook on Irises. Some botanical detective work is necessary to find out why. The error traces all the way back to Linnaeus in his Species Plantarum of 1753, as signalled by the L. after the second part of the Latin name. Linnaeus gave a hybrid a species name.
Linnaeus’ classification system is a phenomenal piece of work. An error could never erode the importance of his work. It is remarkable that we refer back to so much of his groundbreaking work today. Not every aspect of his system has stood the test of time. Our scientific understanding has progressed. Linnaeus’ own work did not emerge from a vacuum. He built upon the foundations of the past too. Taxonomists write Iris Tourn. ex L. when referring to the Iris genus. Tourn. refers to the eminent French botanist, Joseph Pitton de Tournfort (1656-1708). Tournfort introduced plant grouping by genus. Linnaeus was influenced by his work.
The Kew’s Plants of the World online database states Iris x germanica as the accepted Latin name. The introduced x between Iris and germanica signals a hybrid. The subtext states that the range is the North West Balkan Peninsula. Kew lists 36 synonyms. All bear a hybrid x. There are a number of onsite photos and herbarium specimen photos. Many of these are from outside the Balkan Peninsula.
Plants for the Future website shows the common names of Iris germanica L. as Purple Flag, German iris, Orris-root, Tall Bearded German Iris, Bearded Iris. It is notable that common name and photograph show a deep purple-coloured Iris. Colour has already appeared as a key distinction in Irises. The same website notes that: The original habitat is obscure, it is probably of hybrid origin. The hazardous information makes it even more important that a species is correctly identified: The leaves, and especially the rhizomes, of this species contain an irritating resinous substance called irisin. If ingested this can cause severe gastric disturbances. Plants can cause skin irritations and allergies in some people.
Science v. Practical Usage
Not everyone who looks up plant names is an expert taxonomist. Basic plant information needs to be accessible by lay people and even children. Inconsistent or inaccurate plant naming is detrimental to external perceptions and potentially even unsafe. Bearded Irises seem to expose an area of divergence between taxonomists and horticulturalists, science versus daily practical usage.
Latin names are particularly important for the horticultural import and export trade. Common names can vary considerably between countries. The International Code of Botanical Nomenclature (ICBN) governs plant naming. The intention is to have only one correct name. The International Code for Cultivated Plants governs the naming of plants whose origin or selection is primarily due to human activity. A single Latin name with a cultivar name saves confusion. Horticulturalists can know that they are trading in the same plant and help ensure the accuracy of plant passports.
Name clarity is also important at a time when plant health is of rising concern nationally and internationally. Fortunately, Bearded Irises are not regarded as a significant plant health risk. (Root rot and fungal spot are the main risks). Nevertheless, Gardeners get annoyed if they buy a bulb/rhizome and it turns out to be a different plant to the one ordered.
The bilingual Russian-English website of The Iris lays out the interesting, yet complicated efforts over centuries to classify Irises. It describes 9 reviews over the centuries since 1753. There is still no agreement between experts. A future possibility is to exclude rhizomes from the Iris genus. This would mean a significant change for rhizamotous Bearded Irises. The last major classification review was carried out by Brian Mathew in 1981.
The Iris Society’s 1997 publication comments that Iris germanica is unknown in the wild. It is regarded as an enigma. The guide observes that there are a number of near-species that were previously considered distinct. Other problems relate to lack of fertility and seedlings. The Iris can only be pollinated by insects. It resists hand pollination by plant breeders. There is a suggestion that Mathew’s near-species concept is incomplete: a point of view not fully arrived at. Perhaps it should be regarded as significant step on the journey to a review with the benefit of modern-day genetic data?
Despite the classification uncertainty, the glamour of Bearded Irises is undisputed. Plant breeders keep adding new cultivars in their enthusiasm. The range of colourful hybrids befits their namesake, the rainbow goddess Iris.
© Karen Netto (Andrews)
References and Further Reading
Antiss, David (2015): Parts of an Iris Flower. Wikimedia Commons. 28 August 2018. Last accessed 2 May 2020.
Blanco-White, Anne (2017): Breakdown of Iris Species only. British Iris Society. Last accessed 30 April 2020.
British Iris Society (1997): A Guide to Species Irises: Their Identification and Cultivation. Cambridge University Press. Last accessed 3 May 2020.
British Iris Society (2017-?): Bearded Iris. Iris Guide. Last accessed 30 April 2020.
Fraser, Renee (2014): Tall Bearded Iris Color Terms. World of Irises. The Blog of the American Iris Society. 15 December 2014. Last accessed 2 May 2020.
Harbraken, Margie (2017): Anatomy of a Bearded Iris. Sunshine Iris Company. Blog. 23 May 2017. Last accessed 2 May 2020.
Linnegar, Sidney & Hewitt, Jennifer (2005): Irises. RHS Wisley Handbooks. Cassell Illustrated.
Kew Plants of the World Online (): Iris x germanica L. Kew Science. Last accessed 30 April 2020.
Plants for a Future (2010-2020): Iris germanica – L. Last accessed 30 April 2020
RHS (2007): Bearded Iris. RHS Plant Trials and Awards. Bulletin 17. May 2007. Last accessed 3 May 2020
Stewart, Melissa (2013): Classification of Life (Revised Edition). Twenty-first Century Books. Last accessed 3 May 2020.
The American Iris Society (2019): Bearded Irises. Last accessed 30 April 2020.
The Iris (2008-20): Classification of Irises. Last accessed 3 May 2020.