How to Write Plant Species Names Correctly
Correctly writing plant species names is a small detail that carries enormous weight in horticulture, research, and conservation. A single misplaced capital letter or missing comma can reroute a shipment, invalidate a publication, or mislead a gardener into planting a thistle instead of a thyme.
Mastering the rules is easier than it looks, and once you internalize them you’ll never again hesitate over italics, abbreviations, or cultivar punctuation.
Binomial Nomenclature: The Two-Part Latin Label
Every wild plant carries a unique two-word Latin name: the genus followed by the specific epithet. Rosa canina is dog rose, Quercus robur is English oak, and both words together form the species name.
The genus always starts with a capital letter; the epithet never does. Neither word stands alone in formal text; if you mention Quercus by itself, you are talking about the entire genus, not the species.
Italicize both parts in print and handwriting; if your software lacks italics, underline to show the same intent.
Why Italics Matter
Italics signal a foreign-language technical label, distinguishing Cupressus from the English word “cypress.” They also prevent confusion when common and scientific names look similar, such as Morus versus “mulberry.”
Journal editors, nursery catalogues, and patent applications all scan for proper formatting; missing italics can flag a manuscript for automatic rejection.
Capitalization Traps
Never capitalize the specific epithet, even when it honors a person or place. Camellia japonica stays lower-case even though Japan is a proper noun.
The only exception is when the epithet begins a sentence; then the first letter is capitalized and the genus still follows in italics.
Authority Names: The Silent Third Piece
After the binomial you may see a surname or abbreviated surname—Helianthus annuus L. or Magnolia virginiana L.—that credits the botanist who first described the species.
“L.” stands for Carl Linnaeus; other standard abbreviations include “Mill.” for Philip Miller and “Aiton” for William Aiton. These attributions are not italicized, and you can drop them in casual text but must retain them in taxonomic papers.
When two authorities appear in parentheses, it means the species was moved to a different genus after its original description: Cedrus deodara (Roxb. ex D. Don) G. Don signals the shift from Pinus deodara to the cedar genus.
Cultivar vs. Variety vs. Subspecies
A cultivar is a plant selected or bred for gardens; its name sits in single quotes and is never italicized. Hemerocallis ‘Stella de Oro’ and Lavandula angustifolia ‘Munstead’ are classic examples.
Varieties and subspecies occur in the wild; the terms “var.” and “subsp.” (or “ssp.”) appear in roman type between the epithet and the variety name. Acer palmatum var. dissectum keeps the italics on the genus and species, but the variety label is plain text.
Never swap the three categories; doing so implies a different evolutionary history and may breach plant registration rules.
Trade Designation Blues
Nurseries sometimes invent marketing names that look like cultivars but lack single quotes. “Buddleja davidii Purple Emperor” should read Buddleja davidii ‘Purple Emperor’ once the plant is officially registered.
If the cultivar is sold under a protected trade designation, you write the cultivar name first, then the trade label in capitals without quotes: Rosa ‘KORresia’ SUNNY SKYLINE.
Hybrids and Intergeneric Crosses
Hybrid formulas use the multiplication sign: Platanus × acerifolia shows London plane as a cross between P. orientalis and P. occidentalis. The × is not a letter x; it is the Unicode symbol U+00D7.
For bigeneric hybrids, breeders create a new genus name by combining parts of the parents’ names: ×ChitalpaChilopsis and Catalpa. The leading × is not italicized and sits tight against the genus.
When you list multiple hybrids in a table, align the × symbols vertically so the eye can scan parentage at a glance.
Name Changes and Reclassification
Taxonomists move species when DNA evidence rearranges family trees; Senecio cineraria became Jacobaea maritima overnight. Always cite the latest accepted name, but add the basionym in brackets for clarity: Jacobaea maritima (L.) Pelser & Meijden.
Check the International Plant Names Index (IPNI) or World Flora Online before finalizing labels; outdated names can linger in seed catalogues for decades.
When writing for a general audience, you may mention the old name once: “formerly known as Senecio cineraria,” then stick to the current name.
Formatting in Digital Media
HTML italic tags <i> or semantic <em> both render correctly, but choose one and stay consistent. Avoid CSS classes that mimic italics yet fail screen readers; accessibility tools need true emphasis tags to pronounce scientific names properly.
Email newsletters strip formatting unpredictably; send a plain-text fallback that uses underscores: _Rosa chinensis_ ‘Old Blush’. PDFs embed fonts, so embed the italic typeface to prevent default substitution that turns Salvia into Salvia.
Markdown users can asterisk for italics: *Iris sibirica* ‘Caesar’s Brother’, but verify the export pipeline keeps the emphasis intact.
Herbarium Labels and Collection Data
Specimen labels demand absolute precision because they become the reference for future taxonomy. Print genus and species in 10-point italic serif, authority in 8-point roman, and collection details in 6-point sans-serif to create visual hierarchy.
Include GPS coordinates in decimal degrees to four decimals; “41.4034° N, 2.1745° E” pinpoints a Barcelona poppy patch within 11 meters. Never truncate the year; write 2024, not ’24, to avoid century ambiguity.
Use acid-free 100% cotton paper and pigment-based ink; standard dye fades in decades, leaving herbarium sheets illegible.
Patents and Plant Breeders’ Rights
Legal filings require the exact cultivar name as registered with the appropriate authority—U.S. Patent and Trademark Office, CPVO in Europe, or Japan’s Ministry of Agriculture. Misspelling Dahlia ‘Gallery Art Deco’ as ‘Art Décor’ can void protection.
Attach color photographs showing the distinctive traits, and repeat the cultivar name in the image caption exactly as in the application. If the plant is sold under a trademark, the filing must state that the mark is not the cultivar name.
Lawyers prefer the synonym field left blank unless you are proving prior existence; extra names invite challenges.
Common Pitfalls in Garden Writing
Writers often pluralize the genus: “Hydrangeas are stunning” is fine colloquially, but “Hydrangea are stunning” is wrong; the genus is singular even when referring to thousands of plants. If you need a plural, use the English form.
Avoid inventing Latin-sounding names like “Lavandula deluxeiana”; the international code will not recognize them, and satirical hashtags can damage a brand overnight.
Do not translate specific epithets into English in the same sentence: “Helleborus niger, the black hellebore” is acceptable, but “Helleborus black” is nonsense.
Pronunciation Guidance for Speakers
Broadcasters and podcasters fear mangling Latin, yet rules are straightforward: pronounce every vowel and consonant as in classical Latin, not modern Italian. “Clematis” is CLEM-ah-tiss, not cle-MAH-tee; “Kniphofia” sounds nai-FOH-fee-ah.
Stress falls on the penultimate syllable if it is long, otherwise on the antepenultimate: wisteria becomes wis-TEER-ee-ah. Record yourself and compare to Kew Gardens’ online pronunciation clips; consistency beats perfection.
When in doubt, spell the name aloud letter by letter instead of guessing; audiences forgive spelling, not confident mispronunciation.
Citation Styles Across Journals
Annals of Botany wants the full authority on first mention; HortScience omits it unless taxonomic precision is central. Check the author instructions before you submit; copy-editors will not hunt for missing data.
APA 7th edition treats scientific names as common nouns, so no italics in reference list titles: “The ecology of Rosa rubiginosa.” However, the body text still requires italics; the split confounds newcomers.
Chicago Manual allows either italics or roman for plant names in humanities papers; pick one and note it in a style sheet footnote to pre-empt reviewer queries.
Building a Personal Reference Library
Bookmark the Royal Horticultural Society’s Plant Finder for cultivar spelling, Tropicos for synonymy, and Kew’s Plants of the World Online for accepted names. Download the CSV updates monthly; taxonomic churn is constant.
Create a spreadsheet with columns for accepted name, basionym, common name, and source URL; color-code rows by year of last update. Before publishing any article, cross-check every name against your master sheet.
Set a calendar reminder every January to review the previous year’s taxonomic changes; catching reclassifications early prevents embarrassing corrections.