A Plant by any common name...
by Ginny Stibolt

Most folks who work with plants have sometimes been frustrated with common names. Yes, they are easy to remember and pronounce, but there are no hard and fast rules governing them. One plant might be known by several common names depending upon regional traditions and personal favorites.

For instance, when I wrote about beggarticks last year, a reader insisted that they were Spanish needles, not beggarticks. I could choose which common name to use because I liked the play on words, "No need to Beg for beggarticks." They are also known as, Spanish needles, shepherd's needles, butterfly needles, hairy beggarticks, beggar's-ticks, stick-tights, and more. And, there are completely different plants that are referred to using these same names or ones that are confusingly close such as tickseed that normally refers to a coreopsis. Fortunately, the reader, no matter what region or country she lived in, could figure out which plant I was talking about because I also identified it as, Bidens alba.

Classification of Plants

Modern plant taxonomy started in 1753, when Carl Linnaeus published Species Plantarum. He devised a system where the first word in the "scientific" name is capitalized and refers to the genus. The second word refers to the species and is not capitalized, even if the name refers to a proper noun like Woodwardia virginica, Virginia chain fern. 

The scientific naming of cultivars can use two names after the genus name or use an "x" between the genus and the hybrid name. It may be a natural hybrid between two species or it might have been bred for some special characteristics. For instance, the Egyptian walking onion is known as Allium cepa proliferum or Allium x proliferum. The walking onions are prolific as their varietal name indicates. There are also horticultural names such as Magnolia grandiflora "Little Gem." Some plant breeders have trade marked names through the patent office. I won't go into more detail here on the naming of hybrids, cultivars, varieties as it gets complex and not everyone agrees.

While the idea of using Latin or Latinized binomials was not new, Linnaeus was the first to systematically apply them to every plant he saw. He made several plant collecting trips throughout Europe, and he had students and many other botanists (including William Bartram who tromped through our local habitat) collecting plants from far-flung sections of the globe.

Most of Linnaeus's work was accomplished using one or two dried specimens. He would then mark which specimen he used and that is considered the "type" specimen, but it did not have to be a typical or average representative of that species.

Sometimes Linnaeus named plants after people. The genus Commelina, was named after three Dutch botanists in the Commelijn family. Two of them (an uncle and nephew: Jan and Caspar) were productive botanists who were widely published, while the third died at a young age. The three petals of this New World genus usually have two showy petals and one smaller petal, symbolizing the two productive botanists and the other one who was not.

Whenever you see "L." following the Latin binomial, Linnaeus was the first to name it. If there are other letters following his initial, then other botanists have renamed or reclassified the plant, but even today, there are thousands of plants that still carry the names originally devised by Linnaeus.

His methods were quite controversial in his day because his classification groups were based on the sexual parts of the flowers. Linnaeus was aware that this was an artificial classification method, but it allowed botanists to easily determine which plant was which. Linnaeus never developed the concept of families, but later botanists created family groupings for plants to show relationships outside of the genus. For the most part this method of grouping flowering plants has been held up through all these years, even though this method of classification produces some unlikely-looking relatives such as placing Spanish moss (Tillandsia usneoides) in the pineapple family (Bromeliaceae). If you think about Spanish moss being an epiphyte (air plant) as are most of the bromeliads, then you might see the vegetative similarities, though. Today's botanists may also study plants' DNA and other chemistry to look for similarities in the genetics to better group related plants.

Some onions as examples

At first glance it may be difficult to see the family relationship between chives (Allium schoenoprasum) with its spherical head of lavender flowers and meadow garlic (A. canadensis) with its bunch of bulblets and a few white flowers on long stalks. The leaves are different: chives leaves are round and hollow, while the garlic has flat, strap-like leaves. So how can you conclude, other than their odor and/or taste, that they might be related?

Using the Linnaean system, the vegetative parts don't matter–it's all in the flowers. Comparing the individual flowers: they both have six tepals (The term "tepal" is used in this case when the three inner petals look the same as the three outer sepals.), six stamens (the male parts) on long stalks, and an ovary (the female part) divided into thirds. Onions were assigned to their own family, Alliaceae, in the late 1700s. Later taxonomists grouped the onions into the lily family, Liliaceae, because all the members also have six tepals, etc., but most of today's taxonomists place onions in their own family again. Even though the parts of the flowers are similar to lilies, members of the onion family have true bulbs and most produce odorous fumes when cut. True lilies don't have the odors or bulbs–they usually have corms or tubers.

Onions and garlic have been under cultivation for so long, (approximately 5,000 years) that the typical onion (A. cepa) and the typical garlic (A. sativum) are not known in the wild. I purchased some Egyptian walking onion sets two years ago and we've been enjoying these perennial onions both as greens and small bulbs. In two years, I have not seen any flowers, but only the heads with bulblets. If a flower is ever produced though, I know it will have 6 tepals, 6 stamens, and a 3-parted ovary.

Why are they called Egyptian walking onions? Most botanists agree that onions came under cultivation in Egypt. And for this particular cultivar, as the bulblets expand in the flower head shown in this photo, the stem on which they are borne falls over, the new bulbs take root, and the onion then begins to "walk" across the garden. Common names also have interesting stories. I've planted these perennial onions at the edge of a bed, so as I work through the crop rotations each season, the walking onion area remains undisturbed.

Common vs. scientific names

The scientific names are important to gardeners because they identify a plant, even if it's a cultivar. So the next time you see a Latinized binomial associated with a plant, take note of it and write it down for future reference. Otherwise, how will you know what works, and what doesn't, in your gardens and how will you make decisions about future plantings? We should cheer Linnaeus for his industriousness, thoroughness, and his methodology–he's made gardening easier for us, even though we might protest some of those long, unpronounceable names.

Resources:

- For more details on Linnaeus: www.ucmp.berkeley.edu/history/linnaeus.html.
- I've written about our onions before in The Skinny on Onions where I discussed long-day and short day onions and our experiences with them here in Florida.