An introduction to the confusing world of plant names

The newest member of the MPNS, Jason Irving, team explains how he came to discover that using plant names was not as simple as it first seemed...

By Jason Irving

Inside the Temperate House

Discovering and identifying plants 

I first became really interested in plants around four years ago when I started working as a forager, picking wild food to supply to restaurants. My work introduced me to the incredible diversity of plant life in Britain and I became fascinated with the possibilities wild plants presented for use as food, medicine and materials. 

To explore these possibilities for myself I had to be sure the plant I was picking was not poisonous, and that it was the species that tasted nice rather than a flavourless, or foul tasting, relative. This required developing the skill of plant identification; counting the number of petals, describing the shape of a leaf, remembering a smell and spotting many other features. I then had to use this information to differentiate one plant from another. This learning process was given a particular urgency by the knowledge that if I picked the wrong one then I or, even worse, someone else, could be poisoned. 

The confusion of common names 

But identifying a plant as ‘edible’ or ‘tasty’ was not enough on its own. I also had to attach it to a name so that when I spoke with chefs and other foragers everyone would be sure we were talking about the same plant. At first, I assumed one name would be enough. After all I had only ever known one name for the plants I was used to eating: carrot, tomato, spinach and so on. I found out it was not so simple when I phoned another forager in Scotland and asked him 'Is the lady’s smock blossoming?'. He had no idea what I meant. After explaining that I was talking about a plant, that had four pale pink petals and grew by streams, with a distinct flavour of horseradish, he said 'Oh, you mean cuckoo flower?' which was the name he had always known it by. 

I began to look into the names of the plants I was picking, checking books on foraging, wild flowers and herbal medicine, and soon found that one plant could have as many as 30 names! These recorded ‘common names’ were often local to an area, and in the past it was normal for there to be a different name for a plant in each county. This could obviously cause confusion, as not only could people not know the name for a plant in another area, they may actually use the same name for a different plant. One example is ‘old man’s beard’ a name used for at least five different species of plants and lichens with features that resemble white wispy hairs. 

Fortunately, English common names have become more standardised over the years, so at most I would normally only have to learn two or three names for a specific plant. However, these were just the English names which did not help me much when I met a fellow forager from France. I was very keen to find out what he was picking and although he spoke English and I spoke some French we both only knew the names of a handful of plants in each other’s language, and common names usually do not translate well. We tried explaining the appearance and taste of plants we did not know the names for, but found this was a long and laborious way of communicating! 

Scientific plant names - an easy solution? 

Botanists had come up with a solution to these problems some time ago by giving plants names in botanical Latin. These Latin scientific names are recognised internationally as referring to a particular species. I started to memorise some of these scientific names, but I did not have the opportunity to use them much in my work. 

After two years foraging I decided to enrol on a herbal medicine degree to learn more about the effects that the plants I was picking have on the human body. For my first exam I studiously learnt around 100 scientific names of medicinal plants. Equipped with my new-found mental bank of names I thought I had reached a point where I could talk about plants more precisely and find out information about a particular species from around the world. But I soon found out it is not always that simple. 

At the university where I study there is a herbal medicine clinic where students can observe consultations with patients and assist in the preparation of their medicines in the pharmacy. The most common form of medicine is a tincture, an alcoholic extract of a plant, and bottles of these extracts are organised alphabetically by scientific name in the pharmacy. 

One day when I was looking for a tincture of milk thistle (Silybum marianum (L.) Gaertn.) I could not find it in the ‘S’ section. Someone then suggested I look under ’C’ where I found a bottle labelled ‘Milk thistle – Carduus marianus’. It turned out Carduus marianus L. was the scientific name for milk thistle for many years, but that it was later changed to Silybum marianum (L.) Gaertn. The manufacturer was still using the old name to label their product.  

One plant, many names 

This incident introduced me to the problem of synonyms: one species of plant can often have several different scientific names. Because most plants were first named two or three hundred years ago, when global communication was more difficult than today, it was possible for botanists to publish different names for the same plant. Now there are a series of rules for deciding which of these published names to use, which then becomes the ‘accepted name’. 

When I was researching the medicinal actions of a herb for my coursework it was important to find out all the synonyms so I could access all the research done on a species, as just using one name is unlikely to return many results. Studies have shown that just searching on the most used scientific name can return as little as 20% of the research on that species.

Solving the problem 

Kew has been working on several projects aimed at resolving the issues around synonyms and accepted names through the International Plant Names Index (IPNI), The Plant List and the World Checklist

Medicinal Plant Names Services (MPNS) are building on the work of these projects to provide a reliable reference for finding the accepted name for a medicinal plant, and all the synonyms that have been used for it. Significantly it will also include common names used in medicinal plant literature from all over the world, as well as pharmaceutical names that are used in the herbal medicine trade and Pharmacopoeias. This all adds up to a lot of names - at present there are around 140,000 names in the resource for at least 10,000 species. 

I was lucky enough to join the MPNS team last month on a sandwich student placement, so called because I will spend a year here ‘sandwiched’ between the second and third years of my undergraduate degree. It is a great opportunity for me to be able to work at Kew, especially on medicinal plants, and I look forward to helping to build a resource that will make the maze of plant names easier to navigate. 

In future posts I will be exploring the origin of scientific names and their use in herbal medicine, why plant names change, and what names can tell us about plants.

Explore the beta-release of our portal today