Plant Names and Classification Chapter 16

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

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

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)

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)

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

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

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

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

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

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

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

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

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

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

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