By Brandon Gallagher Watson
If you went to any type of forestry, horticulture or arboriculture school, you were inevitably forced to memorize a slew of scientific plant names. Some may have stuck with you throughout the years, but the vast majority of them have likely long since drifted from your easily accessible memory. So, what was the point of that seemingly sadistic exercise? Are scientific names useful to the practicing arborist, or are they simply a way to sound smart about trees to your friends?
Let’s first get in the way-back machine to the mid-1700s. It was the Golden Age of European exploration and colonization, and travelers to all corners of the globe were bringing back flora and fauna specimens by the heap. Naturalists interested in trying to make sense of all the similarities and differences of these samples were stuck with a quandy of classification. Taxonomy, the science of classification, was inconsistent across scientists, schools, countries and continents. As there existed no common language by which to sort, each classifier used a different system with different names. As a result, it was very difficult to systematically catalog the world’s living organisms.
Many attempts to catalog all life have been made throughout history, with records going back before the Greeks, but none were compatible with each other, and the names were still all over the board. Swedish botanist Carl Linnaeus sought to establish a unified classification system when he published “Systema Naturae” in 1758. Linnaeus’s system used a hierarchical organization that started very broadly (such as “is it an animal, vegetable, or mineral?”) and got down to the level of a distinct group of organisms that could successfully breed together, which he called a “species.”
The Linnaean classification system, from broadest to narrowest, goes Kingdom, Phyllum, Class, Order, Family, Genus and Species. Although Carl’s original system has been heavily reorganized during the past century with the advent of techniques such as DNA sequencing, the core categories developed by Linnaeus exist today. Organisms at each level share characteristics of the all the other organisms at the higher level and differ from those at lower levels. All cats are felines, all felines are mammals, all mammals are animals, but not all animals are cats. The grouping of organisms along shared characteristics made it much easier to catalog the ever-growing list of new discoveries from around the world.
Now, what to call all these new discoveries? As plants and animals were being brought back to Europe, some came with names local people called them, those who brought them back named some, and some simply had no common name. Two naturalists could be discussing the same plant but with two different names, so it was ripe for confusion and misinformation. The Linnaean system not only established standard classification, but also established a standard naming system as well. Much to the chagrin of modern natural science students, this system is based in Latin, but at least you can be comforted in knowing that every natural science student around the world has to learn the same system.
Each level in the hierarchy has rules on the suffixes of the names which aid of the ease of use in the system. For example, by convention, every plant name at the Family level must end with the suffix “aceae” (pronounced ACE-E-AY) so their designation can easily be recognized. Each species is designated by its genus and species name, known as its Latin binomial. Properly written, genus is always capitalized, species is always lowercase and both are always italicized. For example, a red maple is a member of the Aceraceae (the maple family) and its binomial should read as [ital>Acer rubrum<ITAL]. Species much like people’s first names, are widely used to describe a number organisms so they should not appear without or at least an abbreviation of the genus (i.e. A. rubrum for our red maple example). Following these standards provides a common language for scientists, naturalists and arborists to discuss a particular organism and ensure we are talking about the same one.
The discoverer traditionally nominates new species names, and if several discoverers name an organism, the earliest published name is considered the “official” name. These names can be one of four types: descriptive, honorary, geographical or historical. A descriptive name will describe some characteristic, such as the red maple, where Acer is Latin for “sharp” referring to the pointy leaves of maples and rubrum is Latin for “red.” Names can honorary, as in the case of twinflower, Linnae borealis, the only plant Linnaeus ever named for himself. They can also signify a place of origin or habitat as in the Japanese beetle, Popilla japonica. Finally, they can be simply named using a historical/ancient name. Names like ginkgo, quercus, and fraxinus are all cultural names that existed before this classification system.
Ranks of Family and higher are commonly named for a marquee member of that group. Apples, pears and serviceberry are all members of the Roseaceae (the rose family) but that that doesn’t signify that these trees evolved from the rose, per se, but that all these species share a common ancestor.
While haters of taxonomy say it’s a practice akin to stamp collecting, in truth, this simple act of attempting to organize life led to the all the great discoveries of biology. Linnaeus was not organizing his chart by evolutionary decent, just by similar morphological characteristics. Charles Darwin looked at the system and wondered how all these different species came about. He came up with The Origin of Species by Natural Selection and reorganized the catalog by shared ancestry. His theories led 20th-Century biologists to discover DNA as the mechanism of change, and they are reorganizing the chart again. It is said that nothing in biology makes sense except in the light of evolution, and there would be no theory of evolution without taxonomy.
Great for the Ivory Tower of Science, but how useful is this to us in arboriculture? For starters, the common naming system serves tree care professionals as well as it does scientists. “Cedar” is one of those common names that applies to dozens of different species, so having a lexicon to distinguish a Thuja from a Juniperus from a Cedrus from a Calcocedrus is very handy. As a general rule, closely related plants have similar characteristics, so even if we have never pruned a Manchurian ash (Fraxinus mandshurica), our experience on native green ash (Fraxinus pennsylvatica) may give us insights that make the job easier and safer. Closely related species are also often susceptible to the same issues, thus we are employing taxonomy when we avoid planting an Austrian pine where a Scots pine just died if we suspect pine wilt nematode was the cause. When we are developing a new rate for a species-specific treatment, such as a tree growth regulator, we look to known rates on their relatives as the starting point.
Knowing taxonomy helps not only with managing trees, but the pests of trees as well. Many of the tools we use to combat insect and fungal pests are specific to a limited group. For example, the neonicotinoids, such as imidacloprid, will easily control insects in the Hymenoptera, Hemiptera and Coleoptera Orders but are not effective on insects in the Order Lepidoptera. This is likely due to a common ancestor of modern moths and butterflies developing a neuro pathway different than the other insects. They lack the same binding sites in their brains that make them susceptible to the neonicotinoid treatments. If you were looking to protect an oak tree from both gypsy moth (a Lepidopteran insect) and two-lined chestnut borer (a Coleopteran insect) with one treatment, your knowledge of taxonomy will help you select a treatment effective for both.
Taxonomy provides the organization and the standardization that was necessary to understand the differences and similarities of life. Although natural science students around the world will continue to dread the memorization of this seemingly foreign language, it is one of the cornerstones of the science of arboriculture. Now, if we can just get homeowners to stop calling all evergreens “pines”…
Brandon Gallagher Watson is director of communications at Rainbow Treecare Scientific Advancements, and is an ISA Certified Arborist (#MN-4086A).