Plant Names and Classification

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 • Dicentracucullaria - 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 Dicentracucullariaand Aconitum species

4. Development of the Binomial System of Nomenclature • 1st attempt to organize/classify plants - Theophrastus(4thcentury 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 • Binomial System of Nomenclature • All species named according to this system, includes authority for species name • Spearmint: Menthaspicata 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 Monerashould 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 12-30 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 • 2ndpart 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 keyshelp 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 methodsused 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 cladograminterpreted 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