6 Jun 2018

Plant names and their practicalities

Kevin McGinn

I’m Kevin McGinn and I’ve recently joined the Botanic Garden as Science Officer in the Growing the Future team. One of our aims is to get more people in Wales growing and appreciating plants, but would-be growers are sometimes scared off by the use of complicated Latin (scientific) plant names. Admittedly, one look at a tongue-twisting scientific name like Trifolium ornithopodioides might be enough to make your eyes glaze over, but hang in there, this blog aims to convince you of their value and help you decipher them!

Common names like forget-me-not and buttercup have many benefits in being charming, culturally important and easier to remember, but they can sometimes lead you down the wrong garden path. The trouble is, plants can have multiple common names that vary from region to region and from language to language, causing confusion and hindering communication. White clover (Trifolium repens), for example, has an abundance of common names across the world in at least 15 different languages, including meillion gwyn in Welsh, witte klaver in Dutch, valkoapila in Finnish and 白三叶 in Chinese. Likewise, Arum maculatum has over 30 common names in English alone, such as jack in the pulpit, cuckoo-pint and lords-and-ladies. At the other end of the spectrum, some plants do not have any common names in any language.

Common names are also sometimes unfitting: Christmas rose (Helleborus), guelder rose (Viburnum opulus) and rock rose (Helianthemum) are, botanically speaking, not roses at all. Entirely different unrelated plants can also share the same common name. Pepper, for example, could refer to bell or chilli peppers belonging to the genus Capsicum, to black/white pepper seasoning produced from Piper nigrum, or even to pink peppercorns from Schinus molle.

The benefit of the two-word scientific system for naming organisms, devised in the mid-1700s by the Swedish botanist Carol Linneaus, is that it provides a universal system. You can think of these two-word names like your family name (known as a genus) followed by your given name (known as a species epithet). A binomial name forms a unique identifier for a plant, ensuring that everyone knows what everyone else is talking about. A gardener in the UK, for example, can email a farmer in New Zealand referring to Cordyline australis (known as Torbay Palm in the UK but as cabbage tree or tī kōuka in its homeland of New Zealand) knowing they are talking about the same plant. In this way, scientific names provide a practical tool as useful as your secateurs!

The Latinised words used for binomial names are often descriptive, based on things like a plant’s physical appearance, habit, origin or habitat. The genus for clover, Trifolium, means three leaflets – no explanation needed for that one! There are around 150 different types of clover (Trifolium) in the world, each one with a different second part to its name (species epithet) to distinguish it. Examples of clover species epithets that give clues to their appearance, illustrated in the accompanying photos, include:

  • fragiferum = strawberry-like
  • glomeratum = with clusters of rounded heads
  • stellatum = starry
  • striatum = with stripes
  • tomentosum = woolly
  • micranthum = with small flowers

The list of enlightening plant species epithets and variations of them is endless, but common ones include:

  • alba = white, as in Nymphaea alba (white waterlily)
  • rubra = red, as in Quercus rubra (red oak)
  • purpurea = purple/pink flowered as in Digitalis purpurea (foxglove)
  • maritima = coastal, as in Armeria maritima (sea pink / thrift)
  • alpinus = from alpine regions, as in Pulsatilla alpina (alpine pasque flower)
  • sylvatica = growing in woodlands, as in Fagus sylvatica (European beech)
  • odoratus = scented, as in Lathyrus odoratus (sweet pea)
  • arborea = woody or tree-like, as in Erica arborea (tree heath)
  • pendula = weeping/hanging, as in Betula pendula (silver birch)
  • dioica = separate male and female plants, as in Urtica dioica (nettle)
  • sativa = cultivated, as in Avena sativa (oat)

An abundance of other plants have been named after people, e.g. Nepenthes attenboroughii is a pitcher plant named after David Attenborough, or named after places, e.g. japonica means from Japan and cambricum means from Wales.

Some scientific names have more than just two parts: subspecies, varieties and forms are named to recognise subtle differences from the typical characters of a species. Cultivars are cultivated varieties, written as Genus species ‘Cultivar’, for example, Quercus robur ‘Fastigiata’. Hybrids are represented by an ×, as in Quercus × kewensis.

Now that you have got to grips with the nuts and bolts of plant names, why not come on one of our Growing the Future courses? For a full list of upcoming Growing the Future courses, including my beginner courses on wildflower and garden plant identification, see here.