You may have noticed that for each plant I always provide the proper scientific name, by which I mean the internationally agreed-upon binomial or Latin name. This is to avoid confusion, because common names for one plant can vary by region and country. For example, any one of the 76 or so plants in the genus Desmodium can go by the name beggar-ticks, beggar’s-ticks, beggar’s-lice, beggar-lice, sticktight, tick-trefoil, tick clover, hitch hikers, and probably others. But if I write about “Desmodium canadense“, there will be no ambiguity. There is only one species with that name.
Desmodium canadense, aka showy tick-trefoil
Worse, the same common name can be used to describe plants that aren’t even in the same family. “Bluebell”, for example, is used for plants in the genera Campanula, Eustoma, Hyacinthoides, Mertensia, Muscari, Phacelia, and Wahlenbergia*. That is about 1,000 different species of plants! And plants in the genus Campanula are also known as “bellflower”…
But the thing that really drives me nuts is the misunderstandings about binomial nomenclature itself, so here’s a little primer.
1. The two words in a binomial name are the “genus” and the “specific epithet”. Together, they make up the species. For example, in Cornus canadensis, “Cornus” is the genus, and “canadensis” is the specific epithet. So please, don’t ever say “genus and species”.
Wrong: “what genus and species is that flower?”
Right: “what species of flower is that?”; or: “I recognize that’s a dogwood; which species is it?”; or if you’re irretrievably pedantic: “I recognize that’s a Cornus; what’s the specific epithet?”
2. The specific epithet is never capitalized, even if it derives from a proper noun or adjective. Therefore, it’s wrong to write Mertensia Virginica even though in standard English we would write it as Virginia mertensia or mertensia of Virginia.
Mertensia virginica white form, aka Virginia bluebells – so much for common names, they’re not even blue!
3. The genus is always capitalized.
4. The species is always written in italics (unless you’re on a lame site like facebook that won’t let you do italics, then you have no choice).
Cornus canadensis in fruit; now you see why it’s called “bunchberry”