1. Plant Names and Classification
Chapter 16

2. Outline
Introduction
Development of the Binomial System of Nomenclature
Linnaeus
The International Code of Nomenclature for Algae, Fungi, and Plants
Development of the Kingdom Concept
Classification of Major Groups
The Species Concept

3. Introduction
All living organisms given two-word Latin scientific name = species name
Only one correct scientific name for species
Many common names may be given to same species
Dicentra cucullaria - Dutchman’s breeches, little- boy’s breeches, monkshood, boys-and-girls, soldier’s cap, white hearts,…, plus others in different languages
Or one common name applied to number of different species
Monkshood for Dicentra cucullaria and Aconitum species

4. Development of the Binomial System of Nomenclature
1st attempt to organize/classify plants - Theophrastus (4th century B.C.)
Classified nearly 500 plants by leaf characteristics
13th century - distinction made between monocots and dicots
Beginning of 18th century - details of fruit and flower structure, in addition to form and habit, used in classification schemes
Latin phrase name given to plants and animals
First word of phrase indicated genus (plural: genera)

5. Development of the Binomial System of Nomenclature
Carolus Linnaeus (1707–1778) - established Binomial System of Nomenclature
Published Species Plantarum, 1753
Changed Latin phrases to reflect relationships and placed one to many species in each genus
Abbreviated names to 2 parts (binomials)

6. Development of the Binomial System of Nomenclature
All species named according to this system, includes authority for species name
Spearmint: Mentha spicata L.
A page from Species Plantarum by Linnaeus

7. The International Code of Nomenclature for algae, fungi, and plants
Book standardizes rules governing naming and classification of plants
Linnaeus starting point for names
Rules revised and expanded at periodic international botanical congresses
Has English, French and German translations
Requires 2 steps to officially recognize new plant species:
English or Latin description or diagnosis must be published in journal or other public publication
Author must designate type specimen deposited in herbarium

8. Development of the Kingdom Concept
When classification schemes first developed, organisms placed in either Plant Kingdom or Animal Kingdom
Distinction works well for complex animals, but not for simpler organisms
Hogg and Haeckel proposed 3rd kingdom in 1860’s
All organisms that did not develop complex tissues placed in Kingdom Protoctista

9. Development of the Kingdom Concept
In 1938, Copeland assigned single-celled, prokaryotic organisms to Kingdom Monera, leaving algae, fungi and single-celled eukaryotic organisms in Protoctista
In 1969, Whittaker developed 5-kingdom system
Split Fungi from Kingdom Protista
In 1980s, Woese argued Monera should be split into Archaea and Bacteria, resulting in 6 kingdoms
Archaea, Bacteria, Protista, Fungi, Plantae, Animalia

11. Classification of Major Groups
3 domains: Bacteria, Archaea, Eukarya
Depending on classification system, between plant phyla recognized
In-between categories, such as subphylum, subclass, suborders subspecies, varieties and forms also used

12. Classification of Major Groups
1st part of species name = genus
2nd part of species name = specific epithet
Specific epithet followed by author(s) who named the plant
Taxonomists specialize in identifying, naming, and classifying organisms
Systematists incorporate evolutionary processes to sort out natural relationships
Dichotomous keys help identify organisms
Choose features from paired statements that most closely apply to organism

13. The Species Concept
Morphological species concept - species defined by morphology
Interbreeding species concept - species a population capable of interbreeding and reproductively isolated from other groups
Ecological species concept - species a group of related individuals that occupy unique ecological niche

14. The Species Concept
Cladistic species concept - species determined by phylogenetic history
Individuals with common evolutionary background = species
Cladistic methods used to determine evolutionary history
Examines natural relationships among organisms, based on shared features
Relationships portrayed on cladograms
Value or form of feature referred to as character state
Hypotheses made about which state ancestral

15. The Species Concept
In trying to choose best cladograms, taxonomists use principle of parsimony
Occam’s razor - “One should not make more assumptions than the minimum needed to explain anything.”
Best cladogram interpreted as that which requires fewest evolutionary changes in taxa involved

17. The Species Concept
Eclectic species concept - single criterion not sufficient to identify species
Morphological, geographical, biological and ecological criteria must be used when defining species
Nominalistic species concept - species do not exist
Evolutionary unit of importance local interbreeding population

18. Review Introduction Development of the Binomial System of Nomenclature
Linnaeus
The International Code of Nomenclature for Algae, Fungi, and Plants
Development of the Kingdom Concept
Classification of Major Groups
The Species Concept