Taxonomy of Flowering Plants - LECTURE NOTES
Hugh D. Wilson
Nomenclature

Nomenclature = the application or assignment of names. A major component of plant taxonomy. Why?

Names provide a cultural or symbolic link to reality and formal scientific names for flowering plants allow a connection to biological reality as expressed by complex systems of classification, i.e., scientific names provide a stable 'handle' and are also rich in information content.

The Magnoliophyta is distributed world-wide as a complex network of ca. 250,000 species. Plant Science is active on a world-wide basis - Chinese physiologists, German ecologists, American Agronomists, British Horticulturists are all working with plant material that can be identified, using the products of plant systematics, to a given species or infraspecific element.  If scientific work is to be repeatable and communicated on a global basis, each species has to be associated with a symbol (species epithet) that is unique, standardized and, via the Genus name, intercalated into the full, content-rich system of botanical classification.



Problems encountered in the pre-scientific (or non-scientific) world:

    1) applying different names to the same plant (independent, uncoordinated naming - analogy with naming bolt 'species' in the first lab)

    2) applying the same name to different plants:   

Buttercup 
(East Texas)
Oenothera speciosa
Buttercup (elsewhere)
Ranunculus sp.

Local names for elements of a local flora are useful and valuable, but only on a local level.  Many elements of a local flora have a broad distribution.  Our 'Spanish Moss' (Tillandsia usneoides - which is Native American - not Spanish - and not a moss) is distributed throughout eastern North and South America, from Virginia to Argentina and it has many local names in several languages.  It is however, a single biological entity and, as a result, it must have only one correct name.

    3) coping with flux resulting from differences in taxonomic opinion (lumping vs. splitting)



Solutions have come about through cooperative development of an international system of plant nomenclature - brief history:

    1) Carolus Linnaeus (overview from UC Berkeley) - initiated a standardized system in the mid-1700s and published SPECIES PLANTARUM (1753) which standardized the binomial as a replacement for descriptive names or polynomials:

        before Linnaeus:   Eupatorium cannabinum, foliis in caule ad genicula ternis, floribus parvis, umbellatim in summis caulibus dispositis, Marilandicum

        after Linnaeus:  Eupatorium purpureum

    2)  Augustin Pyramus de Candolle made first attempt at an international code of nomenclature (early 1800s)

    3) two codes existed in the late 1800s and early 1900s - American vs. European. Aspects of these were argued during international botanical congresses of 1892 and 1910.

    4) 1930 - first International Code of Botanical Nomenclature (ICBN)

    5) subsequent international botanical congresses (ca. every 4-6 years) hear proposals to modify the Code - the most recent congress was in St. Louis, Missouri, USA

    6) each edition of the ICBN is  published in English, French and German - the most recent (2005 - Vienna Code) is available online.

    7) provisions of the ICBN are divided into Rules (firm or binding), set out in the Articles, and Recommendations (non-binding - suggestions)

PRINCIPLES:

    1. "Botanical nomenclature is independent from zoological nomenclature"

    2. The application of names of taxonomic groups is determined by means of nomenclatural types"

    3. "The nomenclature of a taxonomic group is based upon the priority of publication".
      4. "Each taxonomic group with a particular circumscription, position, and rank can bear only one correct name, the earliest that is in accordance with the rules, except in specified cases"     5. "Scientific names of taxonomic groups are treated as Latin regardless of the derivation"     6.  "all rules are retroactive unless expressly limited"


SynonymyFamily; Genus; Species


Why scientific names?

1. local or "common" names cannot be used on a world-wide basis because:

        many names per biological element across its range of distribution
        two or more plants can have the same local name, depending on location
        many species have no local name
        local names are 'language restricted'

2. as opposed to names applied via the ICBN, local or "common" names have no information content relative to the taxonomic system



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