Plant Names

The Binomial System and Cultivars

The name given to a plant species is very important and is the key to identification in the field or garden. Botanical plant names are stable and unambiguous; therefore their use avoids confusion. They are an international form of identity used by researchers and gardeners alike, in an internationally understood language.

Armed with the botanical name, information on a specific plant can be sourced from books and the internet. A botanical name is required before breeders can legally protect the new plants they have bred and also means that the correct plant can be selected and identified in planting schemes. When dealing with medicinal plants and herbs, poisonous plants can be avoided.

Common names that we use for plants, such as daisy, potato and lettuce, are, of course, acceptable in English, but are not universally used. Common names may vary with location – for example, Caltha palustris (Figure X-1) has 140 names in Germany, 60 in France and 90 local names in Britain and Ireland including marsh marigold, kingcups and Mayblobs.

Figure X-1 Caltha palustris | Credit: WikipediaOpens in new window

Alternatively, the same common name can describe several different species. Bluebell is the local name for Campanula rotundifolia in Scotland, Hyacinthoides non-scripta in England, Wahlenbergia saxicola in New Zealand, Clitoria ternate in West Africa and Phacelia whitlava in the USA, none of which are related.

Common names may be in a variety of languages and scripts and often plants are introduced without a common name (e.g. Carmellia sinensis) or with one invented by the seller. A scientific method of naming plants therefore enables every plant to be unambiguously identified with an accurate name that is universally recognized.

The name can also provide information about a species, such as its relationship with other species, and can give clues about its origin, its preferred habitat or its characteristics such as its color, size or form. Linnaeus utilized a naming system which included the name of the genus to which a plant belonged followed by its individual species name written in botanical Latin. This is called a binomial after the two named parts.

For example, the chrysanthemum used for cut flowers (Chrysanthemum morifolium) is in the genus Chrysanthemum and is the morifolium species; note that the genus name begins with a capial letter, while the species has a smaller letter.

Other examples are Ilex aquifolium (holly), Magnolia stellata (star-magnolia) and Ribes sanguineum (redcurrant). The genus and species names must be written in italics, or underlined where this is not possible.

Plants within a species can vary genetically in the wild, giving rise to a number of naturally occurring individuals with distinctive characteristics, much as people vary in their appearance.

Where these differ significantly from the original species they may be given an additional name after the species name and are called a subspecies (subsp.), varieties (var.) or forma (f.) depending on the degree of difference (forma being the least different and subspecies the most).

These extra names are written in botanical Latin and are italicized. They follow the species name, beginning with a small letter and with the category abbreviated and unitalicized in front of them – for example, Hydrangea petiolaris subsp. anomala, Ceanothus thyrsiflorus var. repens, Primula sieboldii f. lactiflora. In addition, cultivation, selection and breeding by humans have produced variations in species referred to as cultivated varieties or cultivars which are distinguished from naturally occurring variants because they have not usually arisen in the wild and must be maintained in cultivation either by specific breeding programmes to produce seed or by vegetative propagation.

The cultivar names can also be written, where applicable, after a common name, often chosen by the plant breeder who produced it, such as Rhododendron arboretum ‘Tony Schilling’ or Cornus alba ‘Sibrica’, and is always a non-Latin (vernacular) name, unitalicized and enclosed in single quotation marks.

Cultivar names can also provide information about a plant’s characteristics, for example, a dessert apple that is suitable for small gardens, ‘Red Devil’, produces bright red fruit; a thornless blackberry, ‘Loch Ness’, was raised in Scotland and shows considerable winter hardiness. This information is useful for gardeners. Penstemon and Pelargnium genēra have the cultivars ‘Apple Blossom’, which describe well the pale pink and white of the flowers. Cultivar names can also be written, where applicable, after a common name, often for fruits and vegetables – for example, tomato ‘Alisa Craig’ and apple ‘Bramley’s Seedling’.

The general term ‘variety’ (which is not the same as ‘varieties’ described above) is often used to refer to any plant type which varies from the original species. As such, it is frequently used interchangeably with ‘cultivar’. In this publication, however, the correct term ‘cultivar’ is used.