The Nature of Nomenclature

Author: Mike Clough

Date Posted: Monday 30th September 2019

So, you’re all highly-qualified horticulturalist and biologists, just like me, and looking forward to some technical discussion? Well, as it happens, I don’t even have a GCSE in biology (my teacher was … well, let’s say we didn’t see eye-to-eye…).

I have come to the study of plants somewhat later in life than I might have done without Mr Duffy’s intervention, and find it genuinely fascinating. I have learned about crops, nutrition, pests, diseases, cultural control, biodiversity, environmental stewardship and some of the specifics of plant biology, as well as how to name plants (which particularly resonates with the English teacher part of me, given its specific requirements on capitalisation).

The beginnings of the modern system of plant naming are usually traced back to Linnaeus’ 1753 work ‘Species Plantarum’, which (re-)introduced the two-part “binomial” names that we use nowadays for all species, like Tyrannosaurus rex, Homo sapiens and favourites of mine, the “tautonyms”, whose generic and specific names are the same, including Bubo bubo, Pica pica, Banjos banjos and Mops mops. Plants are unfortunately prohibited from having tautonyms.

In this system, “families” of plants are grouped together – and under Linnaeus, this was done principally through his method of counting the number of stamens within the flower of the plant – which predictably wasn’t exactly 100% accurate in drawing up a reliable family tree.

Furthermore, drawing the lines between different species is no less complicated in the plant world than the animal kingdom, where some separate “species” who generally breed among their own can still create hybrids between them. Japanese knotweed can hybridise with Sakhalin knotweed and even Russian vine, for example.

While, unsurprisingly, the living world is no respecter of the order we humans (try to) impose on it, molecular biology has resulted in huge jumps in understanding the “tree of life” – particularly in terms of what species diverged from what else and when (a study known as phylogenetics). This understanding has thrown up some unexpected results, to go with some long-understood but counter-intuitive relationships. For example: the tuna is, genetically-speaking, more closely related to a seahorse than it is to a marlin or a sailfish; owls are more closely related to crocodiles, lizards and sea turtles than they are to bats; a salmon is more closely related to a human than it is to a shark; and mushrooms are more closely related to humans than they are to plants!

Many of the phylogenetic groupings have resulted in continued re-ordering of the tree of plant life as it was formerly understood, particularly in Species Plantarum – dividing some species formerly thought to be close relatives, and re-uniting long-lost cousins (aww!).

So, it currently is with the “official” name of Japanese knotweed, which some argue should be “Reynoutria japonica”, rather than the more common name (in the UK at least) “Fallopia japonica”. I have always known the plant as “officially” Fallopia japonica but ask an American, and it may well always have been “Reynoutria japonica” for them. Go back in time and you would see the plant widely referred to as “Polygonum cuspidatum”, the name given to the plant in 1846 by Philip van Siebold, who is credited with bringing Japanese knotweed to the West.

Consensus isn’t even common amongst experts, with many websites including CABI still listing the plant as Fallopia japonica but Wikipedia (the official resolver of pub disputes across the land) headlining with Reynoutria japonica, as do Kew Gardens.

Like all of the natural world, things don’t neatly fit into boxes, and particularly in the plant world, this kind of move from one box to another isn’t actually that uncommon – there is a set of rules called the ICN which determine how a plant should be named, and which covers how disputes should be managed.

Japanese knotweed falls very much into disputed territory, with the various alternative names (or “synonyms” being subject to debate). The website curated by the Royal Botanic Gardens at Kew lists fully nineteen binomial synonyms for Japanese knotweed, in the genera Fallopia, Pleuropterus, Polygonum and Reynoutria.

So forgive me if Japanese Knotweed Solutions don’t rush to change all of our marketing materials – but if you start reading our site and think we’re not all on the same page or don’t know one genus from another, please bear with us while we wait for our phylogenetecists to stop counting stamens long enough to liaise with our search-engine-optimisation team.

“Science” doesn’t get any simpler, or more sensible, really, does it?

Chris Oliver
Operations Manager
Japanese Knotweed Solutions

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Mike Clough

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