Embed Size (px)
Transcript of Plant taxonomy
Definition and BackgroundTaxonomy 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.
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.Importance of Plant Taxonomy
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.
To provide a scientific name to an organism.
To describe the characteristics of a taxon e.g. a family.Taxonomic Components
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.
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.
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.
ANGIOSPERMAEGYMNOSPERMAEDICOTYLEDONEAEMONOCOTYLEDONEAEEUPHORBIACEAE SOLANACEAELEGUMINOSAECRUCIFERAERUTACEAEMALVACEAECUCURBITACEAEPALMAEGRAMINEAEMUSACEAEZINGIBERACEAEORCHIDACEAECYPERACEAESPERMATOPHYTA (SEEDED PLANTS)
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
** 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.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.
THE CONCEPT OF SPECIES1. 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.
CLASSIFICATION SYSTEMSArtificial 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.
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
Scientific name is based on the binomial system
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)
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
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. or Lathyrus spp. (if many species) Scientific name in capital letters and italised is also accepted
CARICA PAPAYA, HEVEA BRASILIENSIS
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. When C.H.
Persoon changed the genus name to Cynodon, the original specific name remains while the original authors 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
- 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
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.
4. Cytology The chromosome number, structure and habit
5. Chemical and molecular Alkaloid, phenolic and amino acids contents. Protein, enzyme and DNA TAXONOMIC CHARACTERISTICS