Plant Cuttings

This image, captioned Adesmia muricata (Fabaceae), by Andrés González is used under the Creative Commons Attribution-Share Alike 4.0 International license.

In the previous post – Did Linnaeus invent binomial nomenclature? – I looked at who should get credit for coming up with binomial nomenclature (Neha Adikane, Paul McCarney), the convention of each species (Neha Adikane) of living things being given a two-word, binomial*, name (Neha Adikane), a so-called scientific name*. For that naming system to work as intended – i.e., so that each two-word name applies only to a single species – the binomials need to be unique. Whilst that’s fine in theory, this post considers how unique those scientific – binomial – names are in practice.

Are binomials unique?

Sort of. I.e., yes – but with some qualification. For organisms within the jurisdiction of a naming authority, such as plants, fungi, and algae governed by the so-called Shenzhen Code, no two species can have the same binomial. Which, in practice also means that names of genera cannot apply equally to a plant, an alga, and/or a fungus. However, organisms whose scientific names are governed by different rules may have organisms with the same binomials as other organisms in another naming group. Binomial names are therefore not necessarily unique.

Rules for binomial names*

There are three major ‘sets of rules’ – international codes of nomenclature – that regulate how species should be named, the International Code of Nomenclature for algae, fungi, and plants (the current version of which is known as the Shenzhen Code), the International Code of Zoological Nomenclature (for animals, including single-celled protozoa from the Kingdom Protista (Regina Bailey) – but excluding algae – whether unicellular or multicellular), and the International Code of Nomenclature of Prokaryotes (for bacteria and archaea). [Ed. – There’s even an organisation dedicated to the naming of non-living viruses, International Committee on Taxonomy of Viruses (ICTV)].

Hemihomony

Where entirely different organisms have the same binomial that is termed hemi homony (Alexey Shipunov, 2011; Jorge Rubén Sánchez-González, 2020; Bob the scientist). Although it’s a situation that appears comparatively rare, it is far from unknown.

E.g., at the level of the genus, we have Buchnera and Ariadne. Buchnera is both a genus of bacteria in the proteobacterial family Erwiniaceae, and a plant in the figwort plant family Scrophulariaceae. And, Ariadne is a plant in the bedstraw/coffee/madder family Rubiaceae [albeit (Eoghan Ryan), Ariadne is a synonym of the currently-accepted name for the plant genus, Mazaea], and a butterfly. [Ed. – these named examples are from the supplementary information to the paper by Jorge Rubén Sánchez-González (2020).] At the species level, we have: Fritillaria gracilis, an animal and a plant; Adesmia muricata, a beetle and a member of the bean family; and Pilophorus clavatus, an animal and a fungus.

Tautonymy

Having excited your interest with mention of plants, animals and fungi with the same binomials, how about tautonyms? A tautonym is a “scientific name of a species in which both parts of the name have the same spelling” (Megan Shersby). Examples, from Shersby, include; the European eel (Anguilla anguilla), and the bird with the English common name of chough (Pyrrhocorax pyrrhocorax) [Ed. – for a longer listing, see here].

Trinomial tautonymy…

And what about the little Jenny wren, a small bird that is so good – and clearly much better than New York – that they named it not twice but thrice, Troglodytes troglodytes troglodytes. The third word of this trinomial indicates a subspecies. [Ed. – if Mr P Cuttings was a zoologist, he might have substituted the western lowland gorilla (Gorilla gorilla gorilla) or the American plains bison (Bison bison bison) for the wren. But, he’s not, he is a Botanist. And, whilst that is the lifeform he would preferentially choose to ‘big up’, he’s happy to provide some animal examples in this post. Because that’s what Botanists do, they acknowledge other lifeforms, they’re not ‘phytoexclusives’ (although they might be ‘botanicosupremacists’…)] [2-Ed –  Hmm, I wonder. Is that really why he’s not provided any plant examples..?]

Plant tautonymy?

But, why, you may well wonder, is this Botanist, in a plant blog, not providing any tautonymous plant examples? That’s because tautonyms are expressly forbidden under article 23.4 of the Shenzhen Code, which states that “The specific epithet, with or without the addition of a transcribed symbol, may not exactly repeat the generic name (a designation formed by such repetition is a tautonym)”.

Which is a great pity, because we Botanists like our nomenclature with a good dose of humour. After all, was it not Carl Linnaeus himself who named a plant Siegesbeckia [Ed. – although more correctly named Sigesbeckia] “that produces a nasty-smelling fluid” (LeeAnn Kriegh) and described it as “a small, useless European weed” (Dawn Todd)? This memorable event took place following a falling-out between the noted Swedish taxonomist and his one-time friend German doctor and botanist Johann Georg Siegesbeck who felt that Linnaeus’ sexual system of plant classification** was ‘repugnant and immoral’, and considered it to be “loathsome harlotry” (Dawn Todd) [Ed. – the moral of which tale appears to be don’t annoy somebody who names plants…].

However, all is not lost. Whilst plants (and fungi and algae) are not allowed to have tautonyms, there is a cunning linguistic way around that. For example, the plant with the English common name of bearberry (Ben Kaplan) has the scientific name Arctostaphylos uva-ursi. Not only is that binomial fun to try and pronounce it holds an example of phytonomenclatural humour, “The genus name of Arctostaphylos uva-ursi comes from the Greek words arctos (meaning bear) and staphyle (meaning “bunch of grapes”) in reference to the fruits which form grape-like clusters.^[3][4][7] In the wild, the fruits are commonly eaten by bears.^[7] The specific epithet, uva-ursi, comes from the Latin words uva (meaning grape) and ursus (bear), reflected by the bearberry nickname.^[7][13]” (this well-sourced answer is from Wikipedia, and is similar to the version intended for younger readers at Kiddle encyclopedia). In other words, both the genus name and the specific epithet mean the same thing – they are effectively tautonyms – but in different languages. Which is a great example of how imaginative and creative Botanists have worked around the “no tautonyms rule”.

* Binomial names (or just binomials (Virginia Holmgren, Michelle Nakano), or binomina (singular, binomen) may also be called Latin names (Priscilla Coulter) or scientific names (Madeleine Barnes), or even taxonomic names.

There are pros and cons for usage of different names for the two-word names of species. Mr P Cuttings is an advocate for the term scientific names because the names themselves aren’t always from the Latin language (Blake Adams, Winifred P Lehman & Jonathan Slocum, Marius Sala et al.).

Although many of the names of genera and/or specific epithets come from Latin (Ronald Coleman), a large number come from Greek (Ronald Coleman) and a host of other languages – e.g. Icelandic, Gaelic, Mongolian, Hebrew, Inuktitut, Japanese, Arabic, Russian (Stephen Heard). Whilst the form of the scientific names – particularly their endings (Ronald Coleman) – must conform to rules of Latin grammar, the names as such are not always Latin (although they may be said to be Latinised). For more on what binomial names should be called, see Stephen Heard, and Alex Bond.

** Human sexual intercourse may not have begun until the annus mirabilis of 1963 – according to British poet Philip Larkin (Kurt Luchs, Vanessa Thorps). But, binomial nomenclature – that naming system forever associated with Linnaeus’ highly sexualised plant classification system*** (Randy Moore, 1997; Staffan Müller-Wille, 2007; Birgitta Bremer, 2008; David Smyth, 2008) – began with the 1753 edition of his Species Plantarum (for plants) [and for animals – although not a sex-based classification, mentioned for good measure – in 1758 in the 10^th edition of his Systema Naturae] (Judith Winston (2018).

*** Which system seemed so scandalous to some that several commentators voiced considerable disquiet about it. But, in at least one case, Linnaeus dealt with that in the best way a taxonomist can – by naming a weedy plant after one of his detractors, Johann Siegesbeck [for more on this, see Plant tautonymy? above]. The sexual nature of Linnaeus’ plant classification was declared “‘too smutty for British ears’, fuelling debates about whether women might be instructed in Linnaean botany without offending female delicacy”” (p. 194, Sam George (2008).

REFERENCES

Birgitta Bremer, 2008. Linnaeus’ sexual system and flowering plant phylogeny. Nordic Journal of Botany 25(1-2): 5-6; https://doi.org/10.1111/j.0107-055X.2007.00098_12.x

Sam George, 2008. ‘Not Strictly Proper For A Female Pen’: Eighteenth-Century Poetry and the Sexuality of Botany. Comparative Critical Studies 2(2): 191-210; https://doi.org/10.3366/ccs.2005.2.2.191

Randy Moore, 1997. Linnaeus & the sex lives of plants. The American Biology Teacher 59(3): 132-132; https://doi.org/10.2307/4450266

Staffan Müller-Wille, 2007. The love of plants. Nature 446: 268-268; https://doi.org/10.1038/446268a

Jorge Rubén Sánchez-González, 2020. Hemi- and Homonyms in the Big Data Era. Diversity 12(12): 472; https://doi.org/10.3390/d12120472

Alexey Shipunov, 2011. The problem of hemihomonyms and the on-line hemihomonyms database (HHDB). Bionomina 4: 65–72; 10.11646/bionomina.4.1.3

David Smyth, 2008. Morphogenesis of Flowers—Our Evolving View. The Plant Cell 17(2): 330–341;  https://doi.org/10.1105/tpc.104.030353

Judith E Winston, 2018. Twenty-First Century Biological Nomenclature—The Enduring Power of Names. Integrative and Comparative Biology 58(6): 1122–1131; https://doi.org/10.1093/icb/icy060