JIM CHATFIELD — SEPTEMBER 1, 2013
A plant identification sign at the Secrest Arboretum in Wooster, Ohio, displays what often can be lengthy -but accurate-nomenclature. Here, names for The Rising SunTM redbud are indicated.
Using appropriate plant names isn’t being pedantic, it’s being accurate. If you know your nomenclature, you can more accurately diagnose problems and find the right solutions. Here, we break down the definitions of the four different plant names and why it matters.
“What’s in a name?’ cries Juliet; ‘that which we call a rose by any other word would smell as sweet.’ Yet Shakespeare might admit that a rose is not less sweet because we know its name.” – Liberty Hyde Bailey from How Plants Get Their Names, 1933.
It is remarkable how often the nuances of names apply to everyday horticulture. From plant selection knowledge to understanding relationships of plants as they relate to propagation and maintenance, from pest management to professional communication with your customers and green industry colleagues, names matter.
Knowing that bacterial fireblight disease occurs only on plants in the rose family, can we assume it occurs on mountainash? Yes, mountainashes (Sorbus spp.) are in the rose family (Rosaceae), and fireblight is a significant problem. Are mountainashes affected by emerald ash borer? No, emerald ash borer insects only affect true ashes in the genus Fraxinus, which are in the olive family (Oleaceae). Understanding names matters.
Click image to enlarge.
And what is the deal with so many plant names? A good example is the sign for a redbud at Ohio State University’s Secrest Arboretum at the OSU Wooster Campus. The sign indicates the redbud in question has four, count them, four names. Let’s begin our discussion here.
The multiple names of plants
Name that tree!
It sounds simple, yet trees have multiple names. Why so many? Let us take a look at the discipline of nomenclature, defined as “the devising or choosing of names for things, esp. in a science or other discipline.” Nomenclature goes hand in hand with taxonomy, “the branch of science concerned with classification, esp. of organisms; systematics.”
The Chinese philosopher Krishtalka wrote, “The beginning of wisdom is calling things by their right name.” Fair enough. But if you have visited an arboretum or botanic garden recently, or if you’ve simply checked out your own nursery or garden center, you will notice that plant labels may have a multitude of names.
Our example is a familiar species, with the common name of redbud. The Latinized botanical name for redbud is Cercis canadensis. The cultivar (cultivated variety) name of our example is ‘JN2’, with a plant patent number often attached to it, in this case PP#21,451. The trademark name of this particular redbud is The Rising SunTM redbud.
Say what? Let us deconstruct.
Common name: Redbud. This is the name most people use for this small native tree, common in Eastern U.S. woodlands, especially as an understory tree in association with flowering dogwoods. It is often noted as the Eastern redbud to distinguish it from the Western redbud (C. occidentalis) and other species in the genus Cercis, such as the Chinese redbud, Cercis chinenesis. It has pinkish buds and wonderful, reddish pink flowers.
Botanical name: Cercis canadensis. The two-part Latin name for the Eastern redbud is also known as the scientific or botanical name for this species. The idea behind scientific names for plants and animals was forwarded by the 18th century Swedish botanist Linnaeus to reduce confusion and improve communication. Don’t believe us? Consider this example cited in Michael Dirr’s Manual of Woody Landscape Plants, in which he indicates that Nymphaea alba has 245 different common names (including European white water lily) in just the four languages of English, French, German and Dutch. This tower of botanical Babel obviously needed a better system. Common names are wonderful, but often communication commands clarity.
Click image to enlarge.
If you understand nomenclature, you understand more than just names. This glorious rhododendron is in the Ericaceae (heath family), which means it will thrive in well-drained, acid soils.
Photos courtesy of Jim Chatfield
Cultivar name: ‘JN2’ (PP#21451), in our example. As horticulturists know, there are many different types of Eastern redbuds; in fact, there is something of a renaissance of redbuds in recent years, from weeping redbuds to purple-leaved redbuds – and weeping, purple-leaved redbuds, to yellow and apricot-leaved redbuds to redbuds with rugose (wrinkled) foliage. This is because horticulturists, practiced in the nurture of nature, have noted variations that come about through genetic recombination and mutations. If they can successfully propagate these new variations, often through asexual propagation, such as clonal cuttings and then grafting to a rootstock, then they may be able to patent their new introduction to the horticultural trade.
Cultivars are designated by single quotation marks. In the case of the redbud in question, its name is sometimes termed a nonsense cultivar name, given that ‘JN2’ is not very descriptive, compared, for example, to the cultivar name of, say, Acer palmatum ‘Bloodgood’, which clearly refers to this old standby of purple-leaved Japanese maple. Why would Jackson Nursery of Tennessee decide to use a nonsense cultivar name (‘JN2’) instead of something more descriptive of what they describe as “A new and distinct variety of Cercis canadensis, an Eastern Redbud tree found and introduced by Jackson Nursery.”? Hmmm?
Click image to enlarge.
Are there any doubts that crabapples belong in the rose family (Rosaceae)? Malus ‘Branzam’, BrandywineT crabapple, boasts rose-like blooms.
Typically the reason for this is that the nursery that introduces a new plant has control of the propagation for sale and other commercial use rights of the plant only for the 20 years afforded by plant patent regulations. After 20 years, other horticulturists can propagate and sell the plants without going through the patenting nursery. Which brings us to …
Trademark name: The Rising SunTM redbud. Jackson Nursery chose as the trademark name a descriptive term that relates to its features of what they describe as “orange new growth developing into bright yellow, then into yellow green, finally maturing into light green with some lighter and darker speckling on the leaves.” We also like their description of “golden tangerine heart-shaped foliage in summer extends through fall; new leaves are bright rosy apricot.” Indeed, that well describes its features – as does the trademark name of The Rising SunTM.
A key factor of trademarks is that they can be renewed, not for 20 years, but rather … forever. This is done because 20 years is often deemed inadequate for recouping the costs of discovery, propagation, production and marketing of a new tree. With the trademark, a plant introducer controls, if not how others commercially use the actual plant germplasm, but at least the commercial use of the name of the plant.
The common name conundrum
So, really, there is a common name which, though often colorful and useful, has no clear-cut rules for use; a botanical name with a set of rules from the Botanical Code of Nomenclature for proper usage (such as the italicized Latin binomial for an organism); a horticultural name for cultivated plants with the rules for naming a cultivar (such as single quotation marks and no italics), and a commericial name reflected by the rules of trademarks.
Common names, as wonderful as they are, may be very unreliable. Consider the red maple, also called the swamp maple. The “swamp” part of the name indicates where it can sometimes be found in natural settings and something about its siting. This maple can tolerate reasonably wet and open sites. But if a customer or a new hire hears or uses the word “red maple,” he may hear or mean a red-leaved Japanese maple or a red-leaved Norway maple. This is cleared up when we term a particular red/swamp maple, Acer rubrum ‘Red Sunset’, that Japanese maple Acer palmatum ‘Bloodgood’, that Norway maple Acer platanoides ‘Crimson King’. Of these, only the Acer rubrum is a good choice for a wet, open site.
Knowing that names matter and that encoded in those names is important information also helps a professional understand that Freeman maples are not just your average red maple, they are actually crosses between red maple (Acer rubrum) and silver maple (Acer saccharinum), and as such have intermediate combinations of growth rate, branch structure, water and drought tolerance, and fall color. Acer × freemanii ‘Autumn Blaze’ is such a hybrid, as are the so-called “rilver” maples that foresters connote when they see hybrids of red and silver maples in the woods.
Viburnum opulus is a European cranberry bush viburnum with sprawling, 12-foot growth; Viburnum opulus ‘Compactum’ is about half that size; and Viburnum opulus ‘Nanum’ is a dwarf of about 2- to 3-foot size. European cranberry bush viburnum as a catch-all does not really do these three plants justice. We have seen many an architect, designer or installer, for example, confuse Viburnum opulus ‘Compactum’ with Viburnum opulus ‘Nanum’, blaming someone else when they do not get what they want, not realizing that they got what they asked for. Names, after all, encode much information.
Alas, those common names. As useful and necessary as they are for everyday communication, common names hold many potential pitfalls. Moss rose, hairy alpine rose, Lenten rose, rose-of-Sharon – none is a rose in the genus Rosa. Liberty Hyde Bailey tells it best. African marigold is from Mexico; Portuguese cypress is from Mexico; Cherokee rose is from China; Arabian jasmine and Spanish jasmine are from India; Spanish cedar is from the West Indies and is not a cedar and not even a conifer (!); Peruvian squill is from the Mediterranean area; the English walnut is not from England; and the French mulberry is not French and not a mulberry.
Yet we are stuck with common names; they will be used, and they are convenient shorthand. Remember, though, their limitations. Unfortunately there is not a routinely standard system of common names for plants, similar to the Entomological Society of America’s Common Names of Insects & Related Organisms. But even with common names, there are some methods that help with communication. Let’s go back to the ashes mentioned above. Mountainash or mountain-ash is properly written as a compound or hyphenated word rather than separate words to cue the reader that it is not a true ash (such as green ash or blue ash) in any way, and this matters with regard to the fireblight bacterium and emerald ash borer host range. Douglasfir is not a true fir. Ladybug beetles are not true bugs, they are beetles. To remember this standard, just think of pineapple, not to stifle hiccups (it works!), but rather to realize that it is written as a compound word to indicate it is neither pine nor apple.
Again, let’s go back to that mountainash. We mention that it is in the rose family (Rosaceae). This leads us to another question about a word – the word “family.” This should not be a casual word for a plant professional. Family means something definitive when it comes to plants. Let’s take a look.
Click image to enlarge.
Woolly alder aphid (Prociphilus tessellatus). The name maple blight aphid, used due to its alternate host, silver maple, is not recognized by the Entomological Society of America in its common names publication. Know your nomenclature!
A FAMILY AFFAIR
For plants and other organisms, a genus is a group of related species. For example, the genus for maple is Acer, which includes such species as red maple (Acer rubrum), Japanese maple (Acer palmatum) and Norway maple (Acer platanoides). What, then, is a plant family? It is a group of related genera (the plural of genus).
Let’s look at the very important rose family (Rosaceae), which includes such genera as:
- Amelanchier – serviceberry
- Aronia – chokecherry
- Cotoneaster – cotoneaster
- Crataegus – hawthorn
- Malus – crabapple and apple
- Potentilla – potentilla or cinquefoil
- Prunus – cherry, almond, plum
- Pyracantha – firethorn
- Pyrus – pear
- Sorbus – mountainash
- Rosa – rose
- Spiraea – spiraea
If you think about the flowers of these genera (forget for a moment the amazing diversity of some of the cultivated roses and think instead of some of the shrub roses), you will note that they are very similar. Think of how similar each crabapple flower is to a rose flower or a Callery pear flower or, for that matter, to individual mountainash florets. In fact, if you think of each floret of a mountainash flower, it is quite easy to see that it is far more related to a spiraea or a firethorn than it is to any of the true ashes in the genus Fraxinus, which are in the Oleaceae.
It should come as no surprise that the reproductive parts of the plants – the fruits, seeds and flowers – provide clues to the relatedness of plants in a given family. It is easy to fool people on plant identification quizzes with the unusual rose-salmon fruits with bright orange seeds of Euonymus europaeus, but when you ask what roadside weed it looks related to, someone in the crowd always says American bittersweet (Celastrus scandens). Both Celastrus and Euonymus indeed are in the bittersweet family (Celastraceae).
This familial relatedness can be used in many ways in practical horticulture. As noted, the disease bacterial fireblight, caused by the bacterium Erwinia amylovora, occurs only on plants in the rose family, especially on Pyracantha, Malus, Pyrus and Sorbus. Symptoms of this disease include blighted shoots of discolored leaves that are bent at the ends in the pattern of a shepherd’s crook. This symptom, of course, also can be caused by other factors. It is a great diagnostic aid, however, to be able to rule out fireblight, even if plants have crooked, blighted shoots, if the plant is a maple (Acer) or an ash (Fraxinus), knowing that these plants are not in the Rosaceae. Or, conversely, to consider fireblight as a possibility if the plant is a mountainash (Sorbus) or a chokeberry (Aronia), since they are in the Rosaceae.
Click image to enlarge.
Fireblight is evident on Pyrus calleryana, Callery pear. Fireblight occurs only in the Rosaceae, of which the genus Pyrus is a member.
Another practical benefit of knowing plant families occurs when there are cultural requirements that sometimes cover most of the plants of a family. A classic case of this is with the heath family, the Ericaceae. Although members of the Ericaceae do vary in terms of their characterization as acid-loving plants, it is not too bad of a generalization to be concerned about planting ericaceous plants such as azaleas and rhododendrons (Rhododendron), Enkianthus, Pieris, mountainlaurel (Kalmia) and blueberry (Vaccinium) in alkaline soils.
Other horticultural practices limited by familial relationships occur as well, from the likelihood of being able to make intergeneric crosses (difficult at best, but more possible between genera in a family), to the likelihood of being able to graft a scion onto a rootstock (if from different genera, more likely between genera in the same family). For example, it seems hard to believe that lilac (Syringa) can be grafted onto privet (Ligustrum) rootstocks until you consider that they are both in the olive family (Oleaceae).
Some families contain only one genus, or even one species, such as Cercidiphyllum japonicum (katsuratree) in the Cercidiphyllaceae. More often than not, though, it is possible to note interesting similarities, for example of fruits, between the multiple genera in a given plant family, such as all the ornamentals in the soil nitrogen-fixing bean family (Fabaceae), including: Cercis (redbud), Cladrastis (yellowwood), Gleditsia (honeylocust), Gymnocladus (Kentucky coffeetree), Laburnum (golden-chaintree) and many more. Think of the bean-like fruits on these trees.
So, names matter, and rules for naming matter. Nevertheless – in the interest of rebellion, if nothing else – we acknowledge, in the spirit of Peter Smithers, who wrote “I consider every plant hardy until I have killed it myself,” this final thought. These are the words of Lewis Carroll, speaking through his characters of Humpty Dumpty and Alice:
“When I use a word,” Humpty Dumpty said in a rather scornful tone, “it means just what I choose it to mean – neither more nor less.”
“The question is,” said Alice, “whether you can make words mean different things.”
“The question is,” said Humpty Dumpty, “which is to be master – that’s all.”
A sense of perspective – and humor – also matters.
Jim Chatfield, Joe Boggs and Pam Bennett are members of the Ohio State University Extension Nursery Landscape and Turf Team. They can be reached at [email protected]; [email protected]; and [email protected] Maria Zampini is president of UpShoot LLC; she can be reached at [email protected]