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Definition and Background

PLANT TAXONOMY. Definition and Background. Taxonomy or systematic is the study or description on variations among organisms in order to come out with a classification system. Organisms that are arranged into groups enable a large population to be categorized and understood.

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Definition and Background

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  1. PLANT TAXONOMY Definition and Background Taxonomy or systematic is the study or description on variations among organisms in order to come out with a classification system. Organisms that are arranged into groups enable a large population to be categorized and understood. Taxonomy began about 300 years before christ by Theophratus (370-285 BC) Carolus Linneaus (1707-1778) is regarded as the founder of taxonomy (father of taxonomy) till today.

  2. Importanceof Plant Taxonomy • To arrange elements or taxa of plants into a more systematic manner so that they can be better understood and could be used easily and more effectively. • 2. To arrange data or information and knowledge about plants. • 3. To indicate the source and genetic relationship (phylogenetic), ancestry and origin of plants. • 4. To indicate the distribution and habitat of plants on earth and their benefits.

  3. Taxonomic Components • Classification Plants are arranged into groups of similar characteristics. The groups are considered as categories or taxa and form the taxonomic system. • Identification • To identify and derive the name of an organism by referring to an existing classification. • 3. Nomenclature • To provide a scientific name to an organism. • 4. Description • To describe the characteristics of a taxon e.g. a family.

  4. Taxonomic System Plant kingdom Animal kingdom Division Phylum Class Order Family Genus Species

  5. Kingdom : • The highest level in a classification e.g. animal and plant kingdom Division : • The number of groups in this taxon is not fixed, it depends on the classification system. • Based on similar characteristics observed on a few elements or organs e.g. : dominance of a sporophyte to a gametophyte, presence of an ovule, seed formation and several other morphological and anatomical characteristics.

  6. Those are hereditary characteristics and will continue to exist from generation to generation. • Class : • The number of groups in this taxon is also not fixed, depending on the classification system. • Separation is based on important basic differences that exist between the groups. Order : • Separation is based on a more convincing genetic relationship which earlier had been detected at the class and division level.

  7. Familiy • Based on more characteristics compared to order, class and division e.g. the morphological characteristics of reproductive organs (inflorescence, ovary position, placentation, number of pistils and carpels, types of ovule and androecium) • Genus • Genus involves more similar characteristics including a closer family relationship but they do not cross. If a hybrid cross does occur the offsprings are normally infertile or will not survive. • Phylogenetically, new genus arises and separates from the same parental origin.

  8. Kingdom Whittaker (1969) : Monera (bacteria, prokaryotic cell) Protista (algae, protozoa, eukaryotic) Fungi (absorb food in liquid form) Plantae(photosynthesis) ** Animalia (ingest food)

  9. PLANT KINGDOM DIVISION: Bryophyta (Mosses: non-vascular) Pterophyta (Ferns: vascular, spores on leaves) Pinophyta (Conifers, Pinus : seeds in cones) Ginkgophyta (Ginkgo : fan-shaped leaves) Cycadophyta (Cycads : palm-liked leaves) Gnetophyta (Gnetum: vessel-filled wood) Magnoliophyta (Flowering plants) : Class: Magnoliopsida (Dicot) Class: Liliopsida (Monocot)

  10. DIVISION (PLANT KINGDOM) SPERMATOPHYTA (seeded plants) PTERIDOPHYTA (ferns) BRYOPHYTA (mosses) THALLOPHYTA (plants with thallus)

  11. SPERMATOPHYTA (SEEDED PLANTS) GYMNOSPERMAE ANGIOSPERMAE DICOTYLEDONEAE MONOCOTYLEDONEAE EUPHORBIACEAE SOLANACEAE LEGUMINOSAE CRUCIFERAE RUTACEAE MALVACEAE CUCURBITACEAE PALMAE GRAMINEAE MUSACEAE ZINGIBERACEAE ORCHIDACEAE CYPERACEAE

  12. CLASSIFICATION OF BANANA KINGDOM: Plantae DIVISION :Magnoliophyta/Spermatophyta CLASS : Liliopsida/Monocotyledoneae ORDER : Zingiberales FAMILY : Musaceae GENUS :Musa SPECIES :Musa acuminata

  13. ENDING OF EACH TAXON FOR THE IDENTIFICATION OF THE CLASSIFICATION LEVEL *(excluding KINGDOM, GENUS and SPECIES) DIVISION : -phyta CLASS : -opsida / -eae ORDER : -ales / -ae FAMILY :-aceae / -ae Sub family :-oideae

  14. SUB AND SUPER CATEGORIES Besides the 7 main categories, there are infra taxa to describe varitions within a taxon: KINGDOM, Subkingdom, DIVISION, Subdivision, CLASS, Subclass, (Superorder), ORDER, Suborder, FAMILY, Subfamily, Tribe, Subtribe, GENUS, Subgenus, Section, Subsection, Series, Subseries, SPECIES, Subspecies, Variety, Subvariety, Form, Subform Example: There are infraspecific categories Subspecies, Variety, Subvariety, Form and Subform to describe variations within Species

  15. Subspecies and Variety : based on morphological variations that can be identified within a species as a result of adaption to different ecology. Form is the category used for only slight variations. **Cultivar the result of crossing over several generations and does not occur naturally. **Clone refers to a uniform population of plants, identical to the mother plant, produced either asexually or naturally.

  16. THE CONCEPT OF SPECIES 1. Morphological species concept • species is the smallest group of organisms • which can be consistently differentiated using • morphological characteristics. • the concept is widely used among taxonomists • as it is the most practical.

  17. 2. Biological species concept • using reproductive biology to define species. • population group which is able to breed but • prevented from gene exchange with population • of other species. • cannot be used for self-pollinated species or • asexually produced species (which do not • undergo crossing)

  18. CLASSIFICATION SYSTEMS • Artificial system • Based on growth habits and uses. A primitive system • 300 BC- AD 1500. Theophratus and Dioscorides, Greece. • 2. Mechanical system • based on one or a few chosen characteristics. 1580-1760. • Caesalpino, Italy; Bauhin, Swiss; Linnaeus, Sweden. • 3. Natural system • Based on many characteristics.1760-1880. Adanson, France; • de Candolle, Swiss; Bentham and Hooker, Britain. • 4. Phylogenetic system • Based on many characteristics, with evolutionary interpretations. 1880-present. Engler, Germany; Bessey, America; Hutchinson, • Britain; Thorne, America.

  19. NOMENCLATURE • Nomenclature is important in order to provide the • correct name for a plant. • The naming activity is under the control of the `International Codes of Botanical Nomenclature’(ICBN) published by the • `International Association of Plant Taxonomy’(IAPT). • The codes are revised at every `International Botanical • Congress’

  20. Scientific name is based on the binomialsystem • popularised by Carolus Linnaeus (1753). Consists of • genus and species names • The third element is the name of the person who • formally gave the name Oryza sativa L. Oryza sativa Linn. (Binomial) Oryza sativa subsp. indica Oryza sativa subsp. japonica (Trinomial) Bupleurum falcatum ssp. eufalcatum var. hoffmeisteri (Quadrinomial)

  21. Populus alba var. canescens Aiton Brassica oleraceae var. capatita Prunus cornuta forma villosa (Trinomial) • Name of genera and that of higher taxon, (Monomial / Uninomial) Rosa L. Rosaceae Juss. • Cultivar taxonomic category Oryza sativa cv. Mat Candu Oryza cv. Mat Candu Padi kv. Mat Candu

  22. For species that have been named earlier it is adequate to name • the species from then on using only the first letter of the generic • name • Solanum melongena, S. melongena • For specific name consisting of two words, a hyphen is needed • between the two words: • Hibiscus rosa-sinensis • If the specific name is not known: • Lathyrus sp. orLathyrus spp. (if many species) • Scientific name in capital letters and italised is also accepted • CARICA PAPAYA, HEVEA BRASILIENSIS

  23. When two or more authors suggest a scientific name, their names are • linked by `et’ • Delphinium viscosum Hook.f et Thomson • The original name for a species is Panicum dactylon Linn. WhenC.H. • Persoon changed the genus name to Cynodon, the original specific • name remains while the original author’s name is placed in bracket: • Cynodon dactylon (Linn.) Pers. • When the first author suggests a name but was officially published by • a second author, both names are linked by `ex’ • Cerasus cornuta Wall ex Royle

  24. HYBRID NAMES • - Interspecific and intergeneric hybrids: • Agrostis x Polypogon • Agrostis stolonifera x Polypogon monspeliensis • Salix auritia x S. caprea • Binary names are given to interspecific hybrids: • Salix x capreola (S. aurita x S. caprea) • Rosa x odorata (R. chinensis x R. gigantea) • A graft between two species uses `+’: • Rosa webbiana + R. floribunda

  25. TAXONOMIC CHARACTERISTICS • Morphology • Plant growth habit, leaf arrangement and shape, flower and fruit characteristics. • 2. Anatomy • Secondary xylem characteristics, epidermis including trichomes and stomata. • 3. Palinology • Pollen characteristics including size, shape, aperture and exine sculpture.

  26. TAXONOMIC CHARACTERISTICS 4. Cytology The chromosome number, structure and habit 5. Chemical and molecular Alkaloid, phenolic and amino acids contents. Protein, enzyme and DNA

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