Anatomy of a botanic label

The plant’s scientific name is the most important part of the plant label,informing visitors and allowing curation by owners and garden staff, and so is always placed in the centre of the label and is shown in the largest font size.

• FAMILY or Family – all letters capitalised, or first letter only capitalised
• Genus – first letter capitalised
• species – all letters in lower case
• infraspecific rank – all letters in lower case or abbreviated with a full stop
• infraspecies – all letters lower case
• ‘Cultivar Names’ – take single quotes with first letter/s capitalised and brackets when after a trade designation
• (Cultivar group) – take no italics, no quotes but placed in brackets

Note on italicisation on plant labels:
For scientific purposes, the genus, species and infraspecies (below the rank of species) names (termed the generic, specific and infraspecific epithets) would be styled in italics and this may be requested by certain botanical institutions in their labelling. However, in general, for garden labelling it is usual practice for such italicisation not to be followed. This dates back to the introduction of the early engraving machines used for labels, for which the range of fonts was limited.

The plant name:
The two-part Latin name (binomial) uniquely identifies the plant from others similar to it. The first name part is the genus and the second, the species. The name of the genus (generic epithet) takes a capital letter, but the species name (specific epithet) following it does not:

Fagus sylvatica        Zinnia elegans         Hyacinthoides non-scripta

Fagus Sylvatica – x        Zinnia Elegans – x         Hyacinthoides Non-scripta x

Where the species is not known, or not needed, this can be indicated by sp. but with no italicisation:
Rosa sp. – ü  Rosa sp. – ü  Rosa sp. – x

For some species of plants, individuals can show a notable variation and where this is the case, a third name or infraspecies (infra-specific epithet) is added to indicate a subdivision of the species; with the ranks of subspecies (subsp.), varietas (var.) or forma (f.). This is added following the rank and is also is shown in lower case. With the limited space on labels, the abbreviated versions are always used.  Note that the ranks themselves, or their abbreviations, are not italicised even where italicisation is used. The rank is often shown in a slightly smaller font than the epithet to improve readability:
Ranunculus bulbilifer subsp. bulbilifer – ü            
Ranunculusbulbilifer subsp. bulbilifer – ü

Ranunculusbulbilifer subsp. bulbilifer – ü
Ranunculus bulbilifer subsp. bulbilifer – x

Cornus kousa var. chinensis – ü
Cornus kousa var. chinensis – ü
Cornus kousa var. chinensis – x

Note:  It is recommended that the abbreviation subsp. rather than ssp. for subspecies is used in order to avoid confusion with spp., which indicates the plural of species. 

To follow the conventions of the International Code of Nomenclature for Cultivated Plants, the use of a generic name (genus) coupled with the cultivar name but without the species name, is incorrect.
Euonymus hamiltonianus subsp. sieboldianus ‘Coral Charm’  – ü
Euonymus hamiltonianus subsp. sieboldianus ‘Coral Charm’  – ü

Euonymus ‘Coral Charm’ –x    Euonymus ‘Coral Charm’ – x

Cultivar names
Many garden plants can also have an additional botanical name or cultivar name (from cultivar and variety). These are selections from species or hybrids which have been bred or selected in cultivation for their horticultural value. Cultivar names can be in any language, and are displayed with a capital letter and within single quotation marks:
Abelia ‘Edward Goucher’- ü      Abelia ‘Edward Goucher’ – ü     Abelia “Edward Goucher” – x

Aster amellus ‘Vanity’ – ü            Aster amellus ‘Vanity’ – ü            Aster amellus “Vanity” – x

Iris  ‘Aichi-no-kagayaki’ – ü         Sedum acre ‘Oktoberfest’ – ü   Iris germanica ‘Nepalensis’ – ü

Myrtus communis subsp. tarentina  ‘Microphylla Variegata’ – ü