Monday, March 11, 2024

Stamp Out Binomial Abuse!

 by Tom Waters

It is said that a little bit of knowledge is a dangerous thing. One manifestation of that pervasive truth is slapping botanical names onto plants where they don't belong. Is it perhaps the urge to seem erudite, or the mistaken notion (propagated in school biology classes), that every organism has a species name, or just unthinking propagation of error, dripping down through the years?

'Absolute Treasure'
Please don't call me I. germanica

I present a list of the four types of irises often identified incorrectly with a botanical species name that does not correctly apply to them. Each of these types is a group of hybrids with ancestry from multiple species. There is no need for a botanical species designation for hybrids of complex ancestry. The tall bearded iris 'Absolute Treasure' is best described---as I have just done---with the classification and registered cultivar name. If classification is clear within context, it can be left out. If one feels more botanically inclined (as might be the case if writing for a technical publication), the correct designation is the genus name in italics, followed by the cultivar name: Iris 'Absolute Treasure'.

Identifying a hybrid with a particular species is not just annoying to those of us with a pedantic streak but can lead to real confusion. People who want to acquire actual species out of botanical interest or for hybridizing, for example, can be sent down time-wasting rabbit holes by this practice, and it is even worse when false botanical names end up in published pedigrees and official descriptions.

So, let's look at the major offenders:

1. Referring to all Siberian irises as Iris sibirica or Iris siberica. This error is reinforced, I think, because of the similarity of the classification name to the botanical name. Most Siberian iris cultivars are advanced hybrids involving I. sibirica and I. sanguinea. The 40-chromosome Siberians do not involve I. sibirica at all.

'Katharine Hodgkin'
Please don't call me I. reticulata

2. Referring to all reticulata irises as Iris reticulata. Yes, there is a species, I. reticulata, sold in the bulb trade and grown in gardens. However, the horticultural group known as reticulata irises includes hybrids and cultivars from a range of species, including I. histrio, I. histrioides, and I. bakerana. Many of Alan McMurtrie's colorful recent hybrids involve I. danfordiae and I. sophenensis. Once again, I think the fact that the common name for the whole group ("reticulata irises") is so similar to the species name I. reticulata is largely to blame for the confusion.

3. Referring to all dwarf bearded irises as Iris pumila. Although the species I. pumila is important in the background of modern dwarf bearded irises, most cultivars are advanced-generation hybrids involving I. pumila and tall bearded iris cultivars in various combinations. Modern standard dwarf bearded (SDB) and miniature dwarf bearded (MDB) irises are far removed indeed from the species. I think part of the problem is that pumila is the Latin word for "dwarf," so people who are not botanically knowledgeable believe they can just translate the term "dwarf iris" to Iris pumila.

Please don't call me I. pumila

4. Referring to all tall bearded irises, or sometimes even all bearded irises of any type, as Iris germanica. Tall bearded irises are advanced-generation hybrids involving many species, most prominently I. pallida, I. variegata, and various tetraploid plants from the Eastern Mediterranean, such as I. mesopotamica. Botanists have differing views about how to apply the name I. germanica, which is unfortunate since it is the type species for the genus Iris. The plant given this name by Linnaeus is a natural hybrid of the intermediate bearded (IB) type. The approach taken by Warburton and Hamblen in The World of Irises is to regard this as a cultivar, not a species (thus 'Germanica'), and to avoid using the term I. germanica entirely. On the other hand, Mathew in The Iris broadens the term to encompass an assortment of similar plants, including many identified as distinct species, such as I. cypriana, I. trojana, and I. mesopotamica. Even taken in this broad sense, however, I. germanica does not include the modern tall bearded hybrids. Given the confusion around using this species name, the best practice is to avoid it in favor of more specific designations for particular plants and populations. Sadly, the use of I. germanica for tall bearded hybrids has become entrenched through generations of misuse, and it is continued unthinkingly by nurseries worldwide.

As a final aside, names that look like species binomials are sometimes used for groups of hybrids. For example, hybrids of I. domestica and I. dichotoma are referred to as Iris ´norrisii, and Iris ´hollandica may be used for Dutch Irises. Note that the "´" is a necessary part of these names. Furthermore, the Latin name for the hybrid group should never be identical to the name of some particular species.

Be wary of these widespread but incorrect uses of botanical names. They not only make it difficult to identify plants correctly but also add to a general confusion concerning the hybrid nature of popular groups of garden irises.


  1. You’re right about the common mis-naming of all Siberian irises as I. siberica when they are usually a mix of species but the correct botanical name for the species itself is I. sibirica not I. siberica.

  2. Thank you, Tom! I so appreciate this clarification. The widespread use of the common name "German Iris" for (usually) tall bearded irises doesn't help matters.

  3. This was unknown to me - I was perpetuating "Iris reticulata 'Harmony'" for example. Really useful and timely post -- many many of us are in the first five years of this knowledge -- thank you!