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Taxonomy

• Taxonomy is one of the oldest, most basic, and all-encompassing of the biological sciences

• It can be controversial and misunderstood

• Taxonomy is both basic because classification is needed to understand variation, and ultimate because it incorporates data from other fields

• Taxonomy possesses an enigmatic aspect and fundamental properties which are both basic and ultimate within biological sciences

• The most basic aspect of taxonomy serves as an entry point to understanding wealth variation

• The ultimate part of taxonomy cannot be complete until data has been incorporated from all other investigative fields

• The dual building and breaking down in taxonomy happens with a continuous process

• Anabolism is the building of complex molocules from smaller simple ones

• Catabolism is the breakdown of larger complex molecules to several simple ones.

• Taxonomy has broad horizons and far-reaching consequences

• Taxonomists play a key role in biological research, medicine, conservation, and food production

Taxonomy: Definition and Process

• Taxonomy is defined as the study and description of organism variation

• It investigates causes and consequences of variation

• Taxonomy manipulates data to make systems of classification

• Classification is a the production of logical system of categories where the categories each contain a number of organisms

• These categories allow for easier reference to the components (or types) of organisms

• Identification is naming as organism using an already existence classification

• Nomenclature is the study of a system for naming organisms

• It includes the construction, interpretation, and application of regulations

• Taxon is any taxonomic grouping such as family, genus, or species that can indicate the rank of a group and the organisms within it

• Description is a statement of an organism/taxon's characteristics

• The Domain of the Rosa acicularis is Eukaryote.

• Its kingdom is Plantae.

• Its phylum is Angiosperms.

• Its class is Rosids.

• Its order is Rosales.

• Its family is Rosaceae.

• Its genus is Rosa.

• The species is Rosa acicularis, also known as the prickly wild rose.

• Diagnosis is a shortened description of a taxon

• It includes diagnostic characters necessary to distinguish it from related taxa

The Cassia fistula L.: A Case Study

• The Family name: Fabaceae
• The Official Common Name: Golden shower
• Description: Leaves are compound, paripinnate, alternate, and the Pinna is ovate, glabrous, and shiny
  • The leaves are coriaceous and entire
  • Apex acute, base rounded.
  • The midrib is prominent and yellowish with obscure lateral and tertiary veins.
  • With capsule fruits , golden yellow flowers and and cylindrical pod fruits
• Its Diagnostic character: Bright yellow flowers in pendulous racemes Trees that drop all leaves during flowering
• Its Distribution: Native to India, Sri Lanka, Myanmar, and Northern Thailand
• It's Uses: Widely cultivated for ornamental and landscaping purposes due to its golden yellow petals

Flora

• flora (lower case initial letter) means the plant life of any given area
• Flora (upper case initial letter) is a book or other work describing the flora of a given area
• It usually provides a means of determining the taxa contained in it
• Floristics is the study of floras, including the preparation of Floras

Experimental Taxonomy or Biosystematics

• Experimental taxonomy is the taxonomic study of organisms from the standpoint of populations instead of individuals
• It examines evolutionary processes within populations
• Biosystematics is a preferable term for experimental taxonomy
• This field focuses on genetical, cytological and ecological aspects of taxonomy studied in field and experimental garden
• Biosystematics refers to a taxonomic application of genecology
• Genecology involves studying the genotypic and phenotypic variation of species to its environment

Approaches to taxonomy

• Orthodox taxonomy relies more often on morphological and anatomical data
• It can be carried out in the herbarium and laboratory
• The two fields of orthodox taxonomy and biosystematics closely interact and are complementary
• Taxonomy is incomplete without either one.

Requisites in the study of Taxonomy

• Phytogeography is a branch of botanical science that studies the distribution of plants on Earth

• Plant phenology is defined as the study of the periodicity of plants as related to climatic events or seasons

• Plant phenology is the study of the life cycle of plants and its prominent manifestations at certain time of the year

• Phenological periodicity depends upon the beginning, duration, and seasonal course of the struggle for existence.

• Striking phenomena, like flowering, fruiting, duration of foliage, leaf fall and the growth of shoots are all very important features in identifying of plants

• Plant morphology is concerned with the study of forms, structures and development of plants

• This includes phytography which describes plant structures and provides terminology for whole plants and their parts

The Development of Western Plant Taxonomy

• Western plant taxonomy has at least five distinct periods: Pre-literate, Ancient literate, Medieval or Dark ages, Renaissance, and Theory of Evolution

Pre-Literate Period

• A pre-written record therefore little direct knowledge had been known of this period
• Archaeological evidences and information from ancient paintings, drawing and utensils suggest that civilization
• This period learned to classify plants according to the basic needs of men for medicine, food, shelter and clothing
• This time civilization learned how to classify which plants were edible and deadly (or poisonous)
• Virtually all civilizations took advantage of the medicinal properties of plants
• In most cultures the medicinal aspects of plants were closely guarded secrets passed on from medicine man to medicine man
• In almost all cultures, even today, medicinal information is concentrated in the hands of a few, whether it be witch doctors, medicine men, shamans or even doctors

Ancient Literate Western Civilization

• The development of writing is a major milestone

• Western taxonomy starts in ancient Greece

• Theophrastus (c. 370-285 BC), a Greek who studied under Plato and Aristotle, is considered the Father of Botany

• He wrote more than 200 works only a few of which survived

• De Historia Plantarum was significant, as was his friendship with Alexander the Great who sent him plants from travels

• Theophrastus wrote about 480 taxa of plants

• He described cotton, pepper, cinnamon, bananas and named modern genera including Asparagus and Narcissus

• Theophrastus is important because of his distinctions between external organs vs internal tissue structures, and between different kinds of tissues

• He is also noted for the classificiation into trees, shrubs, subshrubs and herbs, between flowering and non, and recognizition of different kinds of reproduction

• As well as understanding basic anatomy, he noted that sepals and petals are modified leaves

• He also showed true understanding of fruits

• Pliny the Elder(c. 50 AD) Roman created Natural History (Naturalis Historia), a 37 volume work devoted to Biology

• Most of the botany focused on medicine or agriculture

• He was one of the first to be printed by movable type, his works were read for over 1,000 years

• Pedanius Dioscorides (1st century AD) was a greek contemporary of Pliny who wrote De Materia Medica

• It was an account of plants of medicinal value

• Until the Renaissance (1500's) this was the reference work though the figures bore little resemblance to the original over time

• Since most couldn't read, the copies guaranteed fortune, success, access to practice of pharmacy and medicine

• It recognized some natural families, such as mints and carrots as well as some modern genera such as Aloe

Medieval or Dark Ages

• This period was from the fall of Rome to the Renaissance
• It is called Dark Ages because there was very little original thought or work
• What scholarship there was consisted of copying the ancient works Greeks and Romans
• Unfortunately, this led to considerable loss of information or much misinformation
• Only one botanist of note was Albertus Magnus (St. Albert) c. 1250.
• Magnus employed classification which recognized monocots vs. dicots, as well as, vascular vs. non-vascular

Renaissance

• This period made knowledge available to all

• Botanical-medical books called herbals became popular

• Navigation also began the age of exploration and the number of known plants increased dramatically

• New systems of classification were needed to handle the increase

• Herbalists motivated by practical considerations for medical and agricultural uses of plants

• There were no real systems of classification in this time, rather first hand observation

• Prominent Germans: Otto Brunfels, J. Bock, L. Fuchs (Fuchsia)

• The 17th century caused a massive amount of plants arriving on voyages which necessitated better systems of classification

• Andrea Caesalpino tried to base classification on logic rather than utilitarian concepts (like medicinal uses) He realized some features were more meaningful (priority of floral features)

• During this period Aristotle concepts came into vogue maintaining species were non-varying, and based on ideals

• Gaspard Bauhin (1560-1624, Swiss) Wrote Pinax, registered about 6,000 species that also included synonymy

• Bauhin also had a modern concept of genera and species

• Bauhin experimented with the binomial system of naming plants

• The 18th century found too many new plants that were being described using descriptive Latin phrases

• Carl Von Linne, a Swedish physician, is considered the father of plant taxonomy

• Carl Von Linne created Species Plantarum (1753), and it is the starting point for modern taxonomy.

• Linne realized some characters were more useful and developed Sexual System of classification base on number of parts

• Described 100s of species and used binomials with an L after

• Species Plantarum (01 May 1753) is the nomenclatural starting point

• Natural Systems developed by the late 1700's and tried to reflect natural relationships

• Linnaeus also provided a convenient method, but it was sometimes inaccurate

• Michel Adanson (1727-1806) rejected a priori choice of characters for natural or useful classification

• Therefor Modern computer aided Numerical Taxonomy is called Adansonian Taxonomy

• Antoine-Laurent de Jussieu (1748-1836) arranged plants into a natural system

• Agustin P. de Candolle (1778-1780) A Swiss botanist, he introduced the word taxonomy in his book Theorie Elementarie de la Botanique (1813)

• George Bentham and Joseph Dalton Hooker worked out of Kew Gardens in London and largely established it

• G. Bentham & J.D. Hooker deposited material from early explorations in Kew Gardens

• Bentham & Hooker wrote Genera Plantarum over 20 years which detailed their natural system

Theory of Evolution Era

• Darwin published "On the Origin of Species in 1859."

• This theory was immediately accepted and rapidly became one of the unifying concepts of biology

• Species have evolved from one another over time, meaning species have evolutionary histories

• Species are not represented by ideal types as Aristotle thought, but by variable populations

• Since Darwin's time most systems have reflected evolutionary relationships

• Adolph Engler and Karl Prantl wrote the multi-volume (The Natural Plant Families) from Die Naturlichen Pflanzenfamilien from 1887-1915

• These Germans arranged the plants in an evolutionary sequence ending with the most advanced species

• A major flaw was their assumption that simple equals primitive

• Some plants don't have both sepals and petals, these might be considered as primitive plants

• Information from fossils & anatomy indicates that some primitive flowers had both sepals and petals

• The ones that evolved lost one or both

• Until about 1980 it was the world standard arrangement

• Now replaced by the Cronquist system, and more recently by the APG System (Angiosperm Phylogeny Group)

• The Cronquist and APG are two different approaches to classification of flowering plants

• Both systems aim to organize and categorize based on evolutionary relationships, but differ in methodologies

• The Cronquist system was developed by American botanist Arthur Cronquist, and first presented in "An Integrated System of Classification of Flowering Plants" in 1981

• It relies heavily on observable flower structure, fruit, and leaf arrangement.

• The APG system is a result of collaborative efforts by the Angiosperm Phylogeny Group, an informal group of botanists

• The APG system is based on molecular phylogenetics and incorporates DNA sequence data

• It strives to infer evolutionary relationships among plants in a cladistic approach

• Cronquist relies on morphological features for classification therefore APG uses molecular that to more accurately represent the evolutionary relationships

• Charles E. Bessey from University of Nebraska early devised set of dicta as to which features were primitive and advanced

• Bessey noted primitive features in most ancient plants or recently evolved plants

• Their system of classification based resembled a cactus

• These systems represent data from botany science and anatomy, genetics, physiology, paleobotany, chemistry

• Cronquist gained more wider acceptance and popularity in English

Other Work Influencing Taxonomy

• The floras of Europe and North America went through pioneer and consolidations phases

• Scientists began experimental or biosystematic investigations of plants

• Otto Winge (1917) Denmark demonstrated the utility of using characters of chromosomes

• Winge noted different chromosome numbers in plants e.g. Cytology and cytotaxonomy

• Nils H. Turesson (1920's -30's) a Swedish botanist documented variation and geneceology

• Studies showed adapted ecotypes

• Camp and Gilly 1930-40's wrote on the species concept in plants but there was satisfactory species definition

• Recognized dozen different species types

• Edgar Anderson Clausen, William M. Keck, and William M. Hiesey in 1940s began transplant experiments in California and contributed significantly to the ecotype concept

• Julian Huxley edited New Systematics

• Ralph E. Alston and Billie L. Turner Biochemically studied Systems in 1963

• Peter H.A. Sneath and Robert R. Sokal (1963) collaborated Principles of Numerical Taxonomy

• Utilized classification in maximum predictivity

• Welli Hennig - 1966 translated work phylogenetic analysis rules

• Jeffrey D. Palmer was one of the pioneering botanists

• A.P. group in 1998 showed phylogenetic analyses show morphological nucleotide sequences no longer support the traditional classification of angiosperms into monocots/dicots

• APG has changed fundamental understanding ofdicots and plants.

• The dicots form a paraphyletic complex and characters such as cotyledons, leaves, secondary growth are primitive

• taxonomic activities are largely concentrated in three major areas:

  • Monographs - detailed investigations
  • Floristics - inventories and manuals of plant
  • Biosystematic