tree-logo.gif (7741 bytes) Plant Taxonomy (BIOL308)  -  Stephen G. Saupe, Ph.D.; Biology Department, College of St. Benedict/St. John's University, Collegeville, MN 56321;;


"Must a name mean something?
"Of course it must," Humpty Dumpty said with a short laugh.
"My name means the shape I am - and a good handsome shape it is, too. With a name like yours, you might be any shape, almost."

Through the Looking Glass - Lewis Carroll

I. Definition
System by which plants are named. Or a more fancy definition - determining the correct name of a plant according to a nomenclatural system.

II. Why name organisms?  
    Lewis Carroll knew the answer. Remember Alice's encounter with the Gnat in Through the Looking Glass?

"What sort of insects do you rejoice in, where you come from?" the Gnat inquired.
"I don’t rejoice in insects at all," Alice explained, because I’m rather afraid of them - at least the large kinds. But I can tell you the names of some of them".
"Of course they answer to their names?" the Gnat remarked carelessly.
"I never knew them do it."
"What’s the use of their having names," the Gnat said, "if they won’t answer to them?"
"No use to them," said Alice; "but it’s useful to the people that name them, I suppose. If not, why do things have names at all?"
"I ca’n’t say," the Gnat replied.

Answer (take-home-lesson): "it's useful to the people that name them". Nature doesn't give organisms names, humans do for utilitarian purposes to communicate information about organisms.

    Plants "answer" to their names in the sense that a name provides a way to communicate information. Tippo and Stearn (1977) consider names to be "...indispensable guides to the order of any realm. Names are abbreviated histories, they have dimension in time; they are the beginning points of classification, the designations by which things are known. These are some of what is in a name".

    Imagine how chaotic life would be without names. Remember Alice's adventures in the nameless woods, where nothing had a name...?

"This must be the wood, " she said thoughtfully to herself, "where things have no names. I wonder what’ll become of my name when I go in? I shouldn’t like to lose it at all - because they’d have to give me another, and it would almost certain to be an ugly one. But then the fun would be, trying to find the creature that had got my old name! That’s just like the advertisements, you know, when people lose dogs - ‘answers to the name of ‘Dash’, had on a bass collar’ - just fancy calling everything you met ‘Alice’, till one of them answered! Only they wouldn’t answer at all, if they were wise."

And Alice continued her philosophical discussions....

"I suppose you don’t want to lose your name?"
"No, indeed," Alice said, a little anxiously.
"And yet I don’t know," the Gnat went on in a careless tone: "only think how convenient it would be if you could manage to go home without it! For instance, if the governess wanted to call you to your lessons, she would call out "Come here ____," and there she would have to leave off, because there wouldn’t be any name for her to call, and of course you wouldn’t have to go, you know".
"That would never do, I’m sure," said Alice: "the governess would never think of excusing me lessons for that."

Even Shakespeare has considered the importance of a name (from Romeo and Juliet):

"tis but thy name this is my enemy;
Thou art thyself, though not a Montague.
What's a Montague? it is nor hand, nor foot,
Nor arm, nor face, nor any other part
Belonging to a man. O! be some other name:
What's in a name? that which we call a rose
By any other name would smell as sweet;
So Romeo would, were he not Romeo call'd.

III. Common (or non-technical or vernacular or folk) Names

A. Advantages. Common names have the following advantages:

    1. They are often descriptive (i.e., they describe leaf shape or some other important feature - arrowhead or blueberry; habitat - sea grape or water hyacinth; medicinal value - wormwood);
    2. easy to pronounce;
    3. easy to remember;
    4. more familiar to people;
    5. more pleasing to ear; and
    6. some are just plain fun (gill-over-the-ground).

B. Disadvantages. If common names have so many advantages, then why bother with scientific (or technical) names? Because of the disadvantages, and there are some major ones. Common names:

    1. have no rhyme or reason - they are not governed by rules so there is little consistency from person to person or place to place;
    2. are applied indiscriminately to various taxonomic levels. For example, "oak" could refer to a species, genus or even family;
    3. are not specific. Some plants have more than one common name. For example, Julia Morton (1994) compiled two pages of common names for Lantana camara, Similarly, different plants may have the same common name. Bird names are one exception - the common names are standardized;
    4. may not exist for some plants because they are too rare or obscure;
    5. may reflect language barriers in transmitting the name of the plant (see Kays and Silva Dias, Econ Bot 49: 115 (1995);
    6. may be botanically incorrect. For example, the Jerusalem artichoke is neither from Israel nor is it an artichoke; and
    7. may even be dangerous!  For example, the Chinese star anise (Illicium verum) is edible but the Japanese star anise (Illicium anisatum) is poisonous.

Take-home-lesson: scientific names are preferred because they are exact, the same the world around, and governed by rules. And, as we'll learn later, scientific names also reflect the classification system, and hence the evolutionary relationships of the plants.

C. Common Names Can Matter, or What is Wild Rice? 
    Zizania palustris
is the scientific name for 'wild rice', which is native to lakes and rivers of Minnesota and the upper Midwest. The Ojibway, who called this plant "manoomin", have long harvested the grain and have sold it as a specialty food. Until relatively recently, all commercially-available wild rice was harvested from wild plants using traditional methods. However, in the late 1960's wild rice was 'tamed' and most is now grown in paddies, ironically, largely in California. So, what should this domesticated version of wild rice be called? Many think that 'wild rice' should be restricted to wild-grown grains, especially by many Ojibway who contend that wild-grown rice tastes much better than paddy grown rice. And, not long ago I made a trip to New Zealand and packed several pounds of uniquely Minnesota-style gifts for my friends. The NZ Customs went "wild" when I declared that I was in possession of wild rice and they confiscated all of it, even though it was precooked. For more information check out the article by Walsh (1998).

D.  Good News.
    In a few cases, if you know the common names you are the same as the genus names.  For example:  Iris, T. rex, Asparagus, Begonia, Canna, Catalpa, Euonymus, Forsythia, Ginkgo, Magnolia, Petunia, Phlox, Rhododendron, Sassafras, Verbena, and Viburnum (thanks to Dr. David Hershey for many of these suggestions).

IV. The Rules - Scientific Names

A. The Rule Book
    The rule book for botanical nomenclature is the International Code of Botanical Nomenclature (ICBN).  It is updated periodically at the International Botanical Congresses. The most recent was held in St. Louis in 1999 and an electronic version (called the St. Louis Code) is available.  The previous conference was held in Tokyo in 1993 (the Tokyo Code is also available on-line).   Print versions are also available and are color-coded: purple (Tokyo, 1994), yellow (Berlin, 1988), green (Sydney), red (Leningrad).

B. Some Rules.  

  1. Every plant gets a scientific name; one name per plant (Principle IV - ICBN). 
        Any additional names are synonyms, which must be rejected. Some types of synonyms: (a) Nomenclatural or homotypic synonym - different names based on the same type (see below) specimen. These synonyms exists because botanists examining the same the specimens disagree over naming; (b) taxonomic or heterotypic synonym - different names based on different type specimens. These synonyms exist because botanists examined different specimens of the same plant and devised names without knowledge of the other botanist; (c) homonym - two or more identical names based on different types (i.e., using the same name for different plants).
  2. The scientific name, or more specifically the species name, is a binomial (two names).
        Binominals are combinations of a generic name (genus name) and specific epithet. i.e., Quercus alba is the scientific name or species name for the white oak tree. Quercus is the genus name and alba is the specific epithet.

    Generic names are typically: (a) singular nouns; (b) often descriptive (i.e., relative to habit, habitat, geography, growth, morphology. For example, Liriodendron tulipifera - Lirio = tulip lily); (c) may be derived from other cultures/languages (i.e., Zea mays, Sassafras); (d) commemorate a person or place (i.e., Jeffersonia, Kalmia, Franklinia), except oneself.

    Some genus names are taken directly from Latin (i.e., Acer - maple; Triticum - wheat). Some genus names are even derogatory. For example, Linnaeus named a small unattractive sunflower after a critic, Siegesbeck (Siegesbeckia).

    The genus name is written with the first letter capitalized. It is italicized or underlined, and can stand alone (i.e., Quercus).  The plural of genus is genera. 

    Abbreviations: spp. - more than one species in the genus; sp. one species where the specific species is not designated.

    The specific epithet is typically an adjective that agrees in number and gender with the generic name. It can also be commemorative, descriptive, etc. The specific epithet is written all lower case (except for a few exceptions like some names commemorating a person). Note the specific epithet is always accompanied by the genus name; it cannot stand alone. For example, the specific epithet alba could refer to Quercus alba or Lychnis alba or even another plant.

    Linnaeus is typically given credit for the binomial system. He didn't invent it, but he was the first to consistently use it in Species Plantarum (1753). This system was certainly an improvement over the previous polynomial system. However, these polynomials also served as the "description or diagnosis" of the plant.  For example, the polynomial of the Briar rose (or Dog rose) was Rosa sylvestris alba cum rubre, folio glabro.  This translates into "pinkish white woodland rose with smooth leaves" and was subsequently shortened to Rosa sylvestris (and then changed to Rosa canina).

  1. Names are written in Latin.
        Always italicized or underlined to show foreign word origin. Don't underline the space between the generic name and specific epithet. Principle V - ICBN.
  2. Names must be accompanied by an author citation or authority. 
        This is usually an abbreviation that represents the individual(s) who named the specimen. Thus, the full name for white oak is Quercus alba L. The "L" represents the "parent" of systematic botany, Linnaeus. The author citation is included in the event that it is necessary to track the date of publication of the name to determine if it is valid. (Another curious difference between botanical and zoological nomenclature is that the zoologists do not use author citations, though recently some botanists have begun to question the need for them.).  Check out the Author Name Database by Brummit and Powell.  Family, genus and species names have author citations.

    A parenthetical authority refers to the original author of a name after it has been changed by someone else. For example, Linnaeus named what we know as a hemlock tree as Pinus canadensis. Carriere later recognized that it was a hemlock and not a pine, and transferred it to the genus Tsuga. Thus, the name is Tsuga canadensis (L.) Carr. Linnaeus, the original author, is the parenthetical authority, and Carriere, the new author of the name is the combining authority.  Also note that the specific epithet "canadensis" is conserved and is called the basionym.  It's somewhat similar to what happens when sports teams change cities - LA Lakers are originally from the Twin Cities and the Utah Jazz from New Orleans.

  1. When a plant is named, it must be (a) described in Latin and the author's native tongue.  
        This is called a diagnosis; (b) validly published in a scientific journal; (c) a type specimen must be designated; and (d) the name must be registered (Art. 32. 1-2, Tokyo Code).
  2. The oldest, validly published name, is the correct name (Principle III, ICBN)
        Also called the principle of priority. The starting point for botanical naming is May 1, 1753, the publication date of Linnaeus' Species Plantarum. In some cases, it has been found that a name that is well known is not valid. Rather than change to a more obscure name, the rules permit conserved names, primarily for families and genera. The following table lists families with conserved names.  Either form is correct and you can use whichever you prefer.
    Common Name Traditional Family Name New Family Name
    Grass Family Graminae Poaceae
    Mustard Family Cruciferae Brassicaceae
    Mint Family Labiatae Lamiaceae
    Carrot Family Umbelliferae Apiaceae
    Sunflower Family Compositae Asteraceae
    Palm Family Palmae Arecacaceae
    Garcinia or St. John's Wort Family Guttiferae Clusiaceae

    A good example of the principle of priority is given in Stephen J. Gould's essay, "Bully for Brontosaurus".  Apatosaurus is technically the correct name for this species because it was published first, although rather hastily, beating the name Brontosaurus into press.  The rush to be the first to discover new specimens and name them has, in some cases like this, caused fierce scientific competition and even resulted in sloppy science and sometimes even a little "sleaziness" and back-stabbing. Another good example of the latter is described in Ott's (1976) book and in his rejoinder.

  1. When a plant is named, a specimen that serves as the "reference" or "model" is designated and deposited in a recognized herbarium. 
        This specimen is called a holotype, and this practice is termed the "nomenclatural type system". A duplicate of the holotype is termed an isotype. As an example, assume that you collect five specimens of a particular kind of plant and determine that it is a new species. You select one of the five to serve as the holotype and use it to prepare your Latin description. The other four specimens are isotypes. If a type specimen is absent one of the isotypes can, following rules, be appointed to replace it. Principle II - ICBN.  

    Type specimens didn’t come into use until after the evolutionary paradigm developed. Under the older paradigm of "fixity of species", any specimen would be adequate.  This practice was first adopted in the 1950's.

    There are lots of other kinds of types (don't memorize these): lectotype - specimen selected from the original material to serve as type when the holotype was not designated or if it is missing; neotype - specimen selected to serve as the type when all material on which the name is based is missing; paratype - specimen cited in original description, other than holotype. See Frizzel (1933) for a discussion of additional kinds of type specimens.  By the way, the CSB/SJU Herbarium has one isotype.

  1. Taxonomic ranks have standardized endings (some important ones).
        Kingdom; Phylum or Division - ophyta; Class - opsida; Subclass - idae; Order - ales; Family - aceae; Subfamily - oideae.  An easy mnemonic to remember the ranks: King David cried "Oh, for goodness sake".  You'll recall the Linnean hierarchy from our "Introduction":
    Kingdom   Division  Class  Order  Family  Genus species
    Plantae Magnoliophyta (angiosperms) Magnoliopsida (eudicots) Asterales Asteraceae Taraxacum T. officinale


  2. Botanists do it their own way.
        For example, there are different codes of nomenclature for animals, viruses, cultivated plants, bacteria Principle I - ICBN. For example, tautonyms - a name in which the specific epithet and generic name are the same (e.g., Bison bison is a legal name in zoological, but not botanical circles.

    There is a movement to create a uniform nomenclatural system for all organisms. This "BioCode" is rather controversial and meeting with some resistance in the botanical community because of the many changes that will result.

  1. Writing Sub-specific names.
        When writing names with ranks below species (i.e., subspecies, variety, forma), the abbreviations are not underlined or italicized. Thus - Gleditsia triacanthos forma inermis. Cultivar names, which are used by gardeners and breeders are not scientific names and do not follow the ICBN. The cultivar name is written in single parentheses following the binomial OR using the abbreviation "cv." Example: Malus pumila 'Macintosh' or Malus pumila cv. Macintosh. Cultivar names are not italicized.

V. Botanists may have fun with scientific names
    For example, translate the scientific name of the Caribbean caper, Capparis cynophallophora (Greek kyon = dog; phallos = penis; -phor = to bear).  For a list of humorous scientific names, check out the article by Milus (2001).

VI. Identifying a valid name
    As described above, the correct name for a plant is the oldest, validly published name. Although this sounds simple, in practice it can be challenging to sort through all of the names that have been published for a species and determine which is the correct one. Here's a few tips: (1) list all of the names that have been published for the species in order of publication date; (2) Names with the same specific epithet are usually based on the same type specimen and the latter author knew about the work the work of the earlier author but disagrees with him/her (i.e., nomenclatural synonym; homotypic synonyms); (3) names with different specific epithets are based on different types (i.e., taxonomic or heterotypic synonyms); (4) the oldest specific epithet is conserved unless there is a reason to discard it. As mentioned above, this is similar to the situation in professional sports where the team name is conserved as the team changes cities (i.e., L.A. Lakers); and (5) it may be necessary to form a new name (recombining).

VII. Pronouncing scientific names
    Two simple rules are:  (1) don't accent any syllable; and (2) pronounce each letter.  For additional rules and information check out our text or Stearn's excellent book. The good news is that you can pronounce them however you want. 

VIII. Name changes
    Although it may seem that botanists change scientific names just to frustrate us, this is not the case.  Names are changed because additional scientific study shows that the original name: (1) didn't follow the rules (i.e., wasn't the earliest, or is taxonomic or nomenclatural synonym) or (2) because our taxonomic ideas of the genus and species has changed since the original study (i.e., additional studies showed that two closely related species are actually one). Perhaps this is a good time to mention taxonomists who are "splitters" (focus on the differences between taxa) and those who are "lumpers" (focus on the similarities).

IX.  Ethics of Naming
    Sadly, racism has crept into even plant names.  Consider the following common names:  Niggertoes (=Brazil nuts), Wandering Jew, Coolie's cap, Kaffir lily (in fact, there are 75 South African plants have kaffir in their name), Jew Bush, Pope's nose, and Digger pine (Pinus sabiniana).  Digger pine, native to California, was named as a slur on the natives who "dug" for roots.  Fortunately, we can avoid using these common names.  In fact, Dr. David Hershey reports that in the USDA Plants Database, digger pine has been replaced by California foothill pine.  However, what do we do if the racist word is part of the scientific name, as in Erythrina caffra (Fabaceae)?   It is more difficult to expunge these names since they follow the current "rules." 

    Another interesting example comes from an article in The Week (March 18, 2005) that reported that the Turkish government was renaming three native animals to remove references to Kurdistan and Armenia.  This will be difficult since they want to replace scientific, not common, names.

X. References   

Internet Sites

A.  Course Lecture Notes

B.  Databases

C.  General

So out of the ground the Lord God formed every beast of the field and every bird of the air, and brought them to the man to see what he would call them; and whatever the man called every living creature, that was its name. The man gave names to all cattle, and to the birds of the air, and to every beast of the field…

Genesis 2: 19, 20.

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Last updated:  09/11/2007 / � Copyright by SG Saupe