William Shakespeare, in his play Romeo and Juliet, wrote “A rose by any other name would smell as sweet”. So why does it matter what we call it, then? And why do people like me sometimes get so frustrated when folks use common names instead of the scientific names for plants? In today’s article, I want to explore the benefits, and in some cases the frustrations, of using scientific names for our native plants instead of (or, at least, in addition to) the common names. 

“Latin is a dead language, so why do we use it for plants?” The simple answer – tradition. However, every plant has but one “scientific name”, or scientific binomial, that is unique to that plant, whereas it may have 2 or 3 (and, in some cases, dozens of) common names. What’s worse, the same common name is often used for many different plants.  

For instance, as I pointed out in last month’s blog post, when I talk about Black-eyed Susans, I could be referring to Rudbeckia hirta (an annual/biennial) or Rudbeckia fulgida (a perennial, also known as Orange Coneflower) or even Rudbeckia triloba (a perennial also known as Brown eyed Susan) depending on what part of the country you are in.  

Both Asclepias hirtella and A. viridiflora are called Green Milkweed, though in some locations A. hirtella is known as Tall Green Milkweed – which is what I call it to help me keep the two separate in my mind.  

Is Wild Columbine the same plant as Eastern Red Columbine? Yes, it is. It is also known as Cluckies in some parts. In other areas they call it Jack-in-trousers. But it is also known as Rock Lily. All these common names, yet it has only one scientific name – Aquilegia canadensis.  

Caltha palustris – commonly called Marsh Marigold – has at least 30 distinct common names that I have been able to find, and a whole lot more if you count names that are similar but just spelled differently. Some of these names are just plain weird, if you ask me. Here are just a few of them (in alphabetic order): Boots, Brave Bassinets, Bull Flower, Cow Lily, Cowslip, Crazy Beth, Crowfoot, Drunkards, Goldes, Gools, Horse Blob, King’s Cup, Mare Blob, Marybuds, May Blob, Meadow Buttercup, Meadow Cowslip, Meadow Gowan, Meadow-bright, Mireblob, Publican’s Cloak, Publicans-and-sinners, Soldier’s Buttons, Water Boots, Water Buttercup, Water Cowslip, Water Dragon, Water Goggles, Water Gowan, Yellow Gowan. And that’s just a partial list. Horse Blob??? Crazy Beth??? Where do they come up with these names? 

And then there is Goat’s Rue – a name used for both the rare native Tephrosia virginiana which is considered critically imperilled in Ontario, and the non-native Galega officinalis, considered an invasive species in Pennsylvania. Knowing the scientific binomial can prevent a lot of confusion. It can also keep you from buying the wrong plant. 

But why is it called a binomial? Because the name consists of 2 parts. The first part is the genus (plural genera) – which always starts with a capital letter. The families of plants (e.g. Asteraceae – Aster Family; Laminaceae – mint family; Liliaceae – lily family; Ranunculus – Buttercup family, etc.) are subdivided into genera – which are groupings of similar plants within that family.  

The second part of the binomial is the species name or “specific epithet”, which always starts with a lower-case letter and represents closely related plants within a genus. Example: Asclepias tuberosa. Asclepias tells us this plant is in the genus that contains the milkweeds, and tuberosa tells us which species of milkweed plant it is – in this case Butterfly Milkweed. Note that, by tradition, foreign words (including Latin) are always written in italics. 

A tip for trying to remember the Latin names (though even this is not consistent) is that you can often figure out how the species name ends (is it with an -a, a -um or something else?) by looking at the genus. Latin has feminine, masculine and neuter (neutral) words that may or may not have different endings. Names that end in “-us” are masculine. Words ending in “-a” are feminine, and those ending in “-um” are neutral. So the species name should match the gender of the genus.  

For instance, Purple Coneflower is Echinacea purpurea (feminine) and Sweet Joe Pyeweed is Eutrochium purpureum (neutral) while the South American native Morning Glory was called Convolvulus purpureus (masculine) until they changed the Genus to the feminine Ipomoea and had to change the species to purpurea to match the gender. 

But just to make sure you don’t find this straight forward and starting to make sense, a number of scientific names for plants are based on Greek and not Latin, which have different endings for masculine, feminine and neutral words. And these are less consistent than their Latin counterparts. For example, the feminine ending –a (Monarda) is the same as the Latin, but –ago (Solidago), –e (Anemone), and –is (Anaphalis) are also feminine endings in Greek. Hence you get Solidago juncea, Anemone virginiana, and Anaphalis margaritacaea.  

And though most of the Latin and Greek names are derived from some characteristic of the plant, such as sempervirens – which means “evergreen”, or racemosa – which indicates the flowers are in racemes, many plants are named after prominent botanists, such as Gentiana andrewsii (bottle gentian – named for Henry C. Andrews, 1794-1830) or Geranium bicknellii (Bicknell’s geranium – named for Eugene P. Bicknell, 1859-1925). The –ii at the end indicates the plant is named after a male. Rosa banksiae, the Lady Banks’s rose, on the other hand, is named after Dorothea Lady Banks, the wife of Joseph Banks (1743-1820) who sailed with James Cook on the Endeavour.  But is the feminine usage because the person it’s named after is female? Or is it simply to match the feminine Rosa of the genus? The –ae on the end of banksiae is the plural ending of the Latin –a, though why it is plural is beyond me. 

Confused yet? As they say on those cheap TV commercials – but wait, there’s more! 

“Sometimes I see more than just the two names, and sometimes there is ‘cv’, ‘var.’ or ‘subsp.’ inserted between the names. What does that mean?” The cv is short for cultivated variety, often shortened to cultivar, which is a plant that has been selected for certain characteristics, but normally doesn’t produce true-to-seed. The var. is the abbreviation for variety (varietas in Latin). Botanists will sometimes see that one species has enough genetic variation to separate the plants, but they agree the two plants are still the same species as they can still crossbreed and produce viable offspring – which is one of the defining characteristics of a species. Subsp. is the abbreviation for subspecies – a similar condition. Both are used, but var. is more common in plants, and subsp. is more common with animals. (I don’t make the rules, I just try to follow them as best I can.) 

Are the scientific names carved in stone? I wish! As our science allows us to better understand the genetics of plants, we have been realizing that early botanists didn’t always get it right. Sometimes a plant looks very much like another, so much so that early botanists were convinced they were different species in the same genus. But genetic testing is showing this to not be the case for several species.  

Sometimes they simply move the plant to another genus, as with barren strawberry – formerly Waldsteinia fragarioides, now Geum fragarioides. In some cases, even the species name gets changed, too, as with white snakeroot – formerly Eupatorium rugosum, now Ageratina altissima.  

Sometimes they have to come up with a brand new genus, as they have done for the asters of North America. Aster is now reserved for “old world” asters, as opposed to North American asters. On top of that, we now divide the North American asters into 11 different genera. 

Then there is the Upland White Aster, which for many years was known as Aster ptarmicoides – one look at it will tell you that it is obviously an aster. Then an observant botanist realized that it hybridized with a couple of species of goldenrod, but never with an aster, and they discovered that it was a well disguised goldenrod – so the name was changed to Solidago ptarmicoides or Upland White Goldenrod.  

And   just to make things a bit more challenging, unfortunately not all botanists agree on the name that should be applied to a particular plant, so when you look up a plant online, you may find that the Database of Vascular Plants of Canada, or VASCAN for short calls it one thing, while the Royal Botanic Gardens at Kew calls it something else in their Plants of the World Online. Likewise, iNaturalist claims to follow the Catalogue of Life, but I have found a number of exceptions there, too. Just so you know, as a Canadian I choose to follow the VASCAN nomenclature. 

Pronunciation of all these names is another thing altogether. I found a fairly good online pronunciation resource at https://baygardens.tripod.com/botlatin.html, but here are a couple of great books on Latin for gardeners that I have on my bookshelf and refer to quite frequently. 

Using the scientific name for plants can help because, even if we don’t agree WHICH scientific name is the right one, no two plants will have the same scientific name, whereas one common name can apply to multiple plants. And this can help you get the plant you THINK you’re buying. 

Hopefully you found this little tutorial useful. Your feedback is always appreciated. 

As always, happy native plant gardening.