Classification and Nomenclature


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I. Nomenclature vs. Classification

We are surrounded by a wealth of diversity and one of the goals of systematics is to inventory the amazing magnitude of species on Earth which is estimated to be in the billions; 1.4 billion species have been described; specifically for Wisconsin there are 32,000+, and in terms of vascular plants 2500 spp plus.

The process of identification and then placing names on them is the buisiness of Nomenclature

Classification is placing taxa into a system of retrieval information - usually hierarchical

species -> genus -> family -> order -> class -> phylum

Thus, taxa can be considered groups of organisms at any level.

We will emphasize family, genus and species in this course; but you will see that families are always grouped into orders - this is not for you to learn here!


Typical ending for various ranked names:

  Rank   Ending   Example
  genus   no standard   Rosa
  family  - aceae   Rosaceae
  order   - ales   Rosales
  subclass   - idae   Rosidae
  class   - opsida   Magnoliopsida
  phylum   - ophyta   Magnoliophyta

II. Nomenclature: the naming of things under a system; a system of names

Common names

The advantages of common names include (1) they are easy to remember and descriptive (e.g., stemless lady slipper) and (2) often the only effective way to communicate with general public of species

The disadvantages of common names include (1) one plant can have many names (e.g., stemless lady slipper, moccasin flower, pink lady slipper; garden pansy has over 200+ recorded names); (2) often the same common name can be applied to very unrelated plants (e.g., fireweed for Erechtites in the aster family and Epilobium in the evening primrose family); (3) they can be confusing such that a grapefruit is not related to grapes, a pineapple is neither a pine nor an apple; asparagus fern is not a fern, but an angiosperm; (e.g., some use hyphens to indicate nonrelation of two terms in common name - such as in poison-oak vs. red oak or poison sumac); and (4) lots (most worldwide?) of plants have no common name and thus common names are simply taken from the scientific names (e.g., sedges - Carex buxbaumii - named for Buxbaum - became Buxbaum's sedge!)


Scientific names - e.g., Carex buxbaumii Wahlenb.

The principles and rules of botanical nomenclature have been developed and adapted by a series of International Botanical Congresses and are listed in the International Code of Botanical Nomenclature; the major goal is to provide one correct name for each taxonomic group within a stable system of names

Species names: binomial system is followed which was first consistently used by Carl Linneaus. It is composed of (1) the generic name (Carex) and (2) the species epithet or trivial name (buxbaumii). The species name includes both the genus and species epithet.

Scientific names are formed when an authority(ies) is added to the species or binomial name. The authority is the name of the person or persons who first coined the name for this species. Thus the scientific name is the genus, species, and authority

General rules for binomial


Name changes - production of synonyms

2 case examples; these two examples will be used to demonstrate some of the rules but not all.

Carex buxbaumii Wahlenb. name given to this species of sedge, common in Wisconsin, by Wahlenburg. At a later date, Schkuhr named - what he thought was a new species (maybe from a different region or locality) - Carex polygama Schkuhr. Now, most people consider these two as the same species, and thus the second name is a synonym of the first accepted binomial for this species which has priority in terms of date it was coined.

Senecio aureus L. was named by Linnaeus in the 18th century and describes the golden (aureus) flower of this ragwort. However, just recently, a husband and wife team (Love and Love) considered this species (and other close relatives) to actually belong to another genus Packera. Thus, the accepted name of this species is now :
Packera aurea (L.) Love and Love

Note four things:

1. The name in parenthesis - Linnaeus - is the author of the specific epithet (often called the parenthetical authority), the specific epithet has priority for the new binomial, and is retained when moved into a 2nd genus.

2. Love and Love are the authors of the new binomial name.

3. Notice the gender of the genus has changed, requiring a similar gender ending change in the specific epithet.

4. Senecio aureus is now a synonym of Packera aurea: we will often see these kinds of name changes in floras and can be a source of confusion.

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