There really are very simple rules to follow in how to format these names, and none of these rules are really optional, especially not if you want to promote your company or work as scientific, correct, and professional. Here are the three simple rules:
- Italicize species names
- The Genus name is capitalized in the beginning.
- The species epithet is never capitalized.
For example: Acer, Rudbeckia, and Taraxacum.
The species epithet, the one-word addition to the genus name that creates the species name, should never be capitalized. In the past, sometimes words that originated from place names and people's names were capitalized, but that is no longer done. There is a great website called Curious Taxonomy that lists species named after all kinds of people, such as politicians, sports figures, actors, fictional and mythical characters, things and places around the world.
Examples of correct formatting would be:
americanum, smithii, batesii, and yoda - after America, Smith, Bates, and Yoda.
americanum, smithii, batesii, and yoda - after America, Smith, Bates, and Yoda.
The italicization shows that they are scientific names, and not cultivar names or common names or other informal names. So for a cultivar of a species you would see names like this: Clematis alpina 'Ruby', where the cultivar name is not italicized and in quotes (read more here on cultivar names). To promote the understanding of the biodiversity of the world it is a great idea to have italicized names in concurrence with cultivars, common names and other information. Italicized names are not harder to read, and they are unique, as opposed to common names, and can tell you a lot about the species.
Now, are these three rules followed outside the scientific world? No, not all the time. It is very common to see either no capitalization of genus names or capitalization of species epithets, and the lack of italicized species names are abundant. Here are some examples:
"Thuja Occidentalis" - at least the species name is in italics, but occidentalis should have all been lower case letters. Homeopathic herbal medicine sold by TagAway. (Note, it is homeopathic so it doesn't work, unless it is a placebo effect, link to more information.) (cc) BotanicalAccuracy.com |
LUSH website showing 'Chamomile Blue Oil' with wrongly formatted scientific name. Screenshot by (cc) BotanicalAccuracy.com (link). |
'Pimenta Acris' on the LUSH website, also wrongly formatted. This particular plant and website has been featured on Botanical Accuracy earlier due to taxonomic confusion. Screenshot by (cc) BotanicalAccuracy.com. (link) |
Plant label from University of Oxford's Botanical garden, showing all capitalized scientific name and no italics. © Oxford University, fair use. (link) |
Seed packet label from Renee's Garden for Feverfew, Tanacetum parthenium (listed as Chrysanthemum parthenium). (c) Renee's Garden, fair use (link) |
Scientific names might seem intimidating, but they are very useful and can also be entertaining. For more information and explanations, see this blog post by Benjamin Lord.
Sometimes you see family names italicized and that is not against any rules, but it is becoming less common. I never do it in my scientific writings unless a publisher for a particular journal or book insist on it, and in my experience this is mostly a custom in parts of Europe. It is not a common practice in North America.