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Botanical terms and plant names

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For as long as people have been looking at plants they have been categorising them. First by their size and uses, and then by more precise methods, such as similarities in leaf and flower structure.

By late Renaissance times the increasing range of known plants combined with the rise of scientific knowledge demanded a standardised form of plant classification. The Italian philologist and physician Julius Caesar Scaliger (1484–1558) was among the first to encourage improved classification. However, if botanists in distant countries were to communicate successfully with one another they had to have a common language with accepted terminology. Latin, the language of the Church and scholars, was the obvious choice, but devising a simple terminology to describe the thousands plants known and being discovered every year was a far more complicated task. Several early botanists, such as Andre Cesalpino who published the first modern classification (De Plantis) in 1583 and John Ray (1627–1705), who established the idea of species, created systems but their results lacked consistency and were difficult to understand.

Ultimately the Swedish naturalist Carolus Linnaeus (Carl von Linné [1707–78]) came up with the solution. In his works Systema naturae (1735) and Genera plantarum (1737) he refined identification and classification to the extent that any species of living creature could be classified by just two names, hence his system, still in use today, is known as binomial (two names) nomenclature.

The Linnaean system classifies plants primarily by the characteristics of their reproductive systems. That Linnaeus was able to do this was, as is so often the case with inventions and discoveries, a matter of the right person being in the right place at the right time. As a professor at the University of Uppsala (near Stockholm) in Sweden, Linnaeus had access to the work of previous generations and was free to concentrate on his studies. Also, he worked at a time when scientific principles were becoming widely accepted and scientific instruments, such as microscopes (improved to a workable level by Anton van Leuwenhoek [1632–1723]) and measuring equipment, were rapidly increasing in precision, which enabled detailed observation of the minute components of flowers.

Binomial nomenclature is based on the concepts of genus and species. A genus, the first name, is a grouping of closely related living things that share certain characteristics. A species is a single type of plant or animal within a genus. A species must be genetically stable and capable of reproducing true to type sexually. Natural or artificial hybrids, mutants and selected forms are not regarded as new species.

The genera and species are in turn placed in wider groupings that are increasingly diverse until we return to the entire kingdom of living things. The system as it relates to one plant species, Rhododendron impeditum, is as follows.

Some genera, Rhododendron included, are large, with many complex relationships, so some degree of subdividing within a genus is allowed. Our example, R. impeditum, is a typical small alpine rhododendron from Southern China and may be placed, with others of its type, in a division known as a subgenus, which may be further divided into sections and subsections. The complete description would be something like this; Rhododendron (subgenus rhododendron, section rhododendron, subsection Lapponica) impeditum (series Lapponicum) but for most purposes a simple identification by genus (Rhododendron) and species (impeditum) is adequate. The initial letter of the genus name should be capitalised while the initial letter of the species name should be lower case. The whole botanical name should be italicised.

Natural hybrids or unusual forms may occur and once a plant enters cultivation it is almost certain to be used in hybridisation or developed in some way. Hybrids and cultivated forms fail the first test of a species, they cannot reproduce true to type from seed, so they must be classified in some other way.

Three terms are commonly used to describe these plants; variety, cultivar and clone. Variety is the term commonly used to describe any hybrid or selected form but in botanical terms the definition is more precise. A variety is a naturally occurring variation of a species, this is normally expressed as the abbreviation ‘var.’ as in Rhododendron impeditum var. ‘Blue Steel’. When cultivated it may also be known as a selected form.

You may sometimes see the term subspecies, this is used for plants that are slightly different from the true species that will reproduce true to type. Cultivar (a contraction of cultivated variety) and clone (vegetative replicas of the original cultivar) are somewhat interchangeable terms, they refer to artificially produced hybrids and varieties. Names such as Rhododendron ‘Unique’ refer to cultivars, a plant produced by crossing two distinctly different parent plants and only capable of being perpetuated by vegetative reproduction. Cultivar, clone and variety names are not italicised.

You may have noticed that variety and cultivar names are not in Latin. Before 1958, the year in which The International Code for the Nomenclature of Cultivated Plants was instituted, Latin names were often used but this led to hybrids becoming confused with species. Now all cultivar and hybrid names must be in a language other than Latin. These names may be translated from country to country, so rose known in English-speaking countries as ‘The World’ and German-speaking countries as ‘Die Welt’. Unfortunately the names are not always direct translations, which can be a source of confusion.

Over the years certain conventions in plant naming have developed. If you know the basic rules and understand a little Latin it is often reasonably easy to work out the meaning of plant names, which may give you valuable hints with regard to colouration and habitat preferences. Most names describe some feature of the plant, commemorate a person significant in its history or describe where it was first discovered. Names ending in i, ae, anum usually refer to a significant person. Rhododendron farrerae was named after the wife of an officer of the East India Company. Grevillea banksii was named after Sir Joseph Banks, its discoverer. Names ending in ensis refer to a location, hence sinensis indicates to a plant from China (Sino refers to China) and canadensis is from Canada.

Names ending in um, such as ferrugineum (rust coloured), generally describe a characteristic. Yet other names describe colours, alba (white), rosea (pink), rubra (red) and purpureum (purple) are common examples. The suffix ifera means of, resembling, or used for, so we have papyrifera, used in paper making, and tulipifera, flowers resembling a tulip.

The above are all examples of species names but genus names follow similar patterns. Those ending in ea or ia usually commemorate a significant person, such as Grevillea, named after Charles Greville, a founder of the Royal Society or Banksia, again after Sir Joseph Banks. So in the case of Grevillea banksii both the species and genus forms are used. Dendron means tree, so we have Rhododendron (rose coloured tree), Leucadendron (white tree, after L. argenteum (silver)) and Liriodendron (lily tree). The case of ‘Tulip Tree’(Liriodendron tulipifera) shows two interpretation of what the flowers looks like.

The regularity with which plant names change is a source of constant confusion and frustrates many gardeners, but there are good reasons for it. Often it is because a botanical revision reveals that the relationships between genera and species were not quite as first thought, which necessitates a regrouping and some renaming. If this were not done, just to keep well known names, the situation would soon become very confused with a single plant having several legitimate names.

The second instance in which plants are renamed is an application of the rule of precedence. In the 18th and 19th centuries, when many common plants were classified, botanists had limited opportunities to communicate with one another; there were no international telephone lines and computer networks back then. Consequently there were many instances where a plant had several names because it had been independently classified by different botanists, each of which named it. To eliminate this multiple naming it was decided that the first name given must stand; the first name has precedence over all others no matter how well known or widely used they may be. Some variations are allowed but must follow the conventions laid down in The International Code for the Nomenclature of Cultivated Plants.

The study of plant names can be almost as fascinating as the plants themselves but many people are put off by Latin — some names are larger than the plants themselves — and the seemingly impenetrable mass of names. Try not to become disillusioned with gardening if you can’t master plant naming, the most important thing is that you understand enough to find the information you need.

To help clarify the system and increase your gardening enjoyment the following table lists some of the more commonly used parts of plant names and their meanings. Note that botanical Latin is not classical Latin; it includes many technical terms and words of Greek derivation.

In most cases knowing the genus name will get you on the right track and you may be surprised how many of these you already know. Chrysanthemum, Rhododendron, Camellia and Eucalyptus are all botanical names that are in common use. There may be around 1000 species and countless hybrid rhododendrons but just knowing the genus name is all you need to get started. It’s so much easier to find out information if you know the genus name that it is well worth your while to make the effort to learn a few.

Copyright Geoff Bryant