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The Names of Garden Plants |
Last updated July 2007. Printed version distributed November 2005.
Why are plants named and classified?
We all need names to refer to living things or inanimate objects. To ensure accurate communication, everything needs a unique name; plants are no exception. We also like to classify things, including plants, for different purposes. In a greengrocer, for example, aubergines (eggplants) would be classified as a vegetable and associated with cabbages. However, the aubergine is in the same botanical family (Solanaceae) as the tomato which is a fruit, the Chilean potato tree (Solanum crispum) which is an ornamental climber and deadly nightshade (Atropa belladonna), a poisonous plant. Cabbages on the other hand are related botanically to radishes and wallflowers, and so on. Botanical families indicate similarity in plant morphology and reflect relationships.
Why do we need scientific names?
Through the ages, common names have been given to plants in the language of the area where they grow. Hyacinthoides non-scripta, the western European bluebell, has at least 20 other common names in the UK alone. However, bluebell is also the common name for at least 15 unrelated plants in other English-speaking parts of the world. The use of a single universal scientific name enables everyone to understand one another, whatever their native language.
 Bluebell of England Hyacinthoides non-scripta (Copyright © Helen Miller) |
 Bluebell of Scotland Campanula rotundifolia (Copyright © Mike Grant) |
 Bluebell creeper of Australia Sollya heterophylla (Copyright © RHS Herbarium) |
What do the parts of a scientific name mean?
Take as an example Digitalis purpurea. The first word is that of the genus (plural genera), which includes all foxgloves. If it causes no confusion, the genus name may be abbreviated to its initial letter when repeated in text. The second word is the species (plural species). These two words together (the binomial) refer uniquely to the purple-flowered foxglove of W. Europe, whereas D. grandiflora is a yellow-flowered species from C. & S. Europe. Sometimes a species is subdivided into subspecies (subsp.), varieties (var.) or formas (f.); for example, white-flowered variants of the purple foxglove may be called D. purpurea f. albiflora.
What is a cultivar?
Many garden plants have originated as chance seedlings, complex hybrids or sports from species which have been selected for horticultural use. These can be named as cultivars (from cultivated variety). For example, a foxglove with variegated leaves has been given the name Digitalis purpurea 'Chedglow'. If there can be no confusion, the genus and cultivar names may be used without the species name. Solanum tuberosum 'King Edward', Solanum 'King Edward' and even potato 'King Edward' are equally correct. However, 'King Edward' alone could be confused with the unrelated Achillea × lewisii 'King Edward'.
 'King Edward' (Copyright © RHS Herbarium) |
 'King Edward' (SASA © Crown Copyright) |
What is a hybrid?
A cross made between plants of two different species results in a plant called a hybrid; it may be given its own scientific name. Thus Digitalis × mertonensis is the hybrid name for all plants derived from the cross between D. purpurea and D. grandiflora. The "×" indicates the hybrid status. Many different cultivars may result from the same cross.
 D. purpurea (Copyright © RHS Herbarium) |
 D. × mertonensis (Copyright © RHS Herbarium) |
 D. grandiflora (Copyright © RHS Herbarium) |
What are trade designations (selling names)?
Sometimes the correct cultivar name is not considered attractive, so one or more extra names are chosen for marketing. These are known as trade designations and their use is often associated with plants which have received legal protection by Plant Breeders' Rights. However, the correct cultivar name must always be included on the plant label. The correct cultivar name for the popular yellow-leaved Choisya ternata is 'Lich', but the plant is marketed as C. ternata 'Lich' SUNDANCE. A cultivar name, however unwieldy, must not be translated, but if this unfortunately occurs, the translation will not be a cultivar name but a trade designation, e.g. Clematis 'Błękitny Anioł' BLUE ANGEL.
Clematis 'Błękitny Anioł' BLUE ANGEL
(Copyright © RJE)
What is a synonym?
Synonyms are outdated or alternative names. Pelargonium peltatum is the correct name nowadays for the plant which was first called Geranium peltatum (now a synonym) by Linnaeus in 1753. Linnaeus's name was coined before the two genera, Pelargonium and Geranium, were separated by another botanist, L'Héritier, in 1789.
What are authorities (authors)?
The authority (author) is the name of the person (or people) who first described and published the species. It comes after the scientific name. Linnaeus (usually abbreviated to "L.") is the author of Digitalis purpurea L. Authorities are rarely used with cultivar names; they are most frequently used in botanical
literature.
How is a plant name written?
There is an internationally recognised convention for writing plant names. The scientific (Latin) part of a name is in italics (or underlined), but all other parts of the name are in ordinary Roman type. The genus name has an initial capital letter (as do authorities), but other parts of the scientific name do not. With a very few exceptions, all words within a cultivar name start with a capital letter and the complete name is enclosed in single quotation marks, e.g. Lavandula stoechas L. subsp. pedunculata (Mill.) Rozeira 'Purple Ribbon'. The abbreviations "cv." or "×" are not used before a cultivar name. Trade designations (selling names) are not surrounded by quotation marks but should be given a different type face, e.g. Clematis 'Evipo001' WISLEY.
How is a new cultivar name chosen?
There are a few simple guidelines to follow when selecting a suitable new name. Fuller details are given in the International Code of Nomenclature for Cultivated Plants (ICNCP) or 'Cultivated Plant Code'.
How is a cultivar name published?
To be accepted, every new cultivar name must be published. This is important to prevent another use for the same name. Any dated, printed publication such as a nursery catalogue, journal or book is acceptable. The name must be accompanied by a short description in a modern language distinguishing the new cultivar from all others. Names first used on plant labels or electronic media, such as Web sites or CDs, are not considered to be properly published.
An unnamed rose seedling
(Copyright © Diana Miller)
How can a plant or its cultivar name be protected?
A plant may be legally protected by Plant Breeders' Rights so that the owner or his representative has the sole right to propagate the plant and receive royalties on all plants sold. Details may be found at http://www.upov.int/. For information specific to the UK, contact DEFRA, The Plant Variety Rights Office and Seeds Division, White House Lane, Huntingdon Road, Cambridge CB3 0LF or visit http://www.defra.gov.uk/planth/pvs/
The cultivar name of a plant can be protected by registering it with the appropriate International Cultivar Registration Authority (ICRA). For information contact the International Commission for Nomenclature and Cultivar Registration of the ISHS (International Society for Horticultural Science), through The Royal Horticultural Society's Garden, Wisley, Woking, Surrey GU23 6QB or visit http://www.ishs.org/icra/
Sending a sample of a new cultivar to a herbarium specialising in cultivated plants will help to ensure that your new plant will not become confused with others in the future. The RHS Herbarium at Wisley, Woking, Surrey GU23 6QB will accept specimens and a Nomenclatural Standard will be prepared from them. A Nomenclatural Standard, together with any relevant information, forms that cultivar's Standard Portfolio.
Standard Portfolio of Rhododendron 'Maurice Daffarn'
(Copyright © RHS Herbarium)
More detailed information on plant names may be found in a guide published in March 2007 by HORTAX and available on this Web site. See Plant Names - a guide for Horticulturists, Nurserymen, Gardeners and Students.
All information on this page and in the guide to plant names may be copied and distributed free of charge.
The 7th edition of the International Code of Nomenclature for Cultivated Plants (Cultivated Plant Code) @ €55 is published by ISHS 2004, Acta Horticulturae Number 647, ISBN: 90 6605 527 8. It is available from ISHS, PO Box 500, 3001 Leuven 1, Belgium or http://www.ishs.org/sci/icracpco.htm
The latest International Code of Botanical Nomenclature (Vienna Code) 2006, published by Koeltz Scientific Books, PO Box 1360, D-61453 Königstein, Germany for the International Association for Plant Taxonomy (IAPT) can be obtained from any good bookshop @ £40.00 / €60.70 / $80.09. ISBN: 3 906166 48 1. It can also be consulted on-line at http://www.ibot.sav.sk/karolx/kod/0000Viennatitle.htm
HORTAX gratefully acknowledges financial support from the Stanley Smith (UK) Horticultural Trust.
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