3. TAXONOMY
ā¢ Taxonomy is the science that explores, describes, names, and classiļ¬es all
organisms. In this introductory slide, I will highlight the major steps in the
elaboration of this science that provides baseline data for all ļ¬elds of biology and
plays a vital role for society but is also an independent, complex, and sound
hypothesis-driven scientiļ¬c discipline.
ā¢ Plant taxonomy is the science that finds, describes, identifies, classifies, and
names plants. The term Systematics is applied to the study or description of
variations among organisms in order to formulate a classification system.
Organisms thus arranged into groups enable a large population to be categorised
and understood. Plant taxonomy or Sytematics has undergone through four major
approaches of study. These could be summarized as: 1) Pioneer or Alpha: This
phase was early periods that involved explorations and discovery of new plants.
2) Consolidation: In this phase, the large amount of data collected was organised
to understand classification.
5. WHAT IS TAXONOMY
ā¢ 3)Synthesis: During this phase, the consolidated data and adequate plant material
collected was classified principally based on morphological characters. It attained
its peak by late 1800ās and to some extent still continues. 4) Experimental: Using
different scientific tools and modern technology, the vast amount of collected
data interpreted in evolutionary or phylogenetic terms is being currently analysed.
This phase is still evolving.
ā¢ OBJECTIVES
ā¢ i) to provide a convenient method for identification and communication;
ā¢ ii) to produce a coherent and universal system of classification;
ā¢ iii) to provide a single Latin āscientificā name to every plant and groups of plants
in the world, both living and fossil.
ā¢ iv) to maintain inventory of the world flora; and
ā¢ v) to demonstrate the evolutionary implications of plant diversity; There are
four important steps in taxonomy:
7. STEPS OF TAXONOMY
ā¢ There are four important steps in taxonomy: 1. CHARACTERISATION 2.
IDENTIFICATION 3. CLASSIFICATION 4. NOMENCLATURE
ā¢ These are the primary activities of a taxonomist. Characterisation is the basic
requirement for understanding the different parts of the organism. It is thus a
description of the characters. By comparing the characters of two or more
organisms, it becomes possible to differentiate them. This leads to identification.
When two or more organisms have been differentiated (identified) by their
characters, it becomes necessary to group them into categories. This is essentially
what taxonomists do when they classify organisms. Once the identified
organisms have been classified, it becomes necessary to name them. Thus the
process of taxonomy is a logical sequence of knowing (1) the characters of the
organisms; (2) identifying them on the basis of an understanding of their
characters; (3) classifying them into groups; and (4) providing them name
9. IDENTIFICATION
ā¢ It is the determination of the group to which a specimen belongs.The process usually
includes a direct compariszonof an unkown specimen with the already classified,
circumscribed, and named taxa.The process includes the use of keys-of various types,
computer based methods and variety of polyclave species.It is done by the following
methods:
ā¢ i. The determination of the similarities and differences between two specimens,
ā¢ ii.The direct comparison of the features of a specimen in hand with those in keys in order
to arrive at a name,
ā¢ iii.he assignment of an unidentified taxon to a correct class in an established system of
classification,
ā¢ iv. The determination of a name for a particular specimen in relation to an established
system of classification,
ā¢ Mostly the morphological characters along with anatomy, phytochemistry, cytology,
palenology and molecular data are involved for the proper identification of the unknown
spercimen.
11. NOMENCLATURE
ā¢ Nomenclature is a very important constituent of plant taxonomy. It can be defined
as the system of naming an object particularly that of biological origin. We are
aware that man has been interested in plants since prehistoric times. The plants
have been given names by tribes in their own languages. These are called
common or vernacular names.
ā¢ Arrangement of definite names to plants is called nomenclature & it involves the
principles governed by rules formulated and adopted by ICBN listed frormally in
a code .The major goal of ICBN is to provide one correct name for each taxon-
the unit of taxonomy.
ā¢ Although a number of rules are addressed in the nomenclature of plants but the
binomial system is based on C. Linnaeus(1707-1778), the swidish naturalist in
the first edition-Species Plantarum.The name comprises two parts-
ā¢ Generic name & Specific epithet following some rules.
ā¢ e.g. Oryza sativa L. of Rice
13. CLASSIFICATION
ā¢ Classification always follows identification. Thus when two or more groups of plants
have been differentiated (identified) from their characters, it becomes necessary to
recognize their relationships. This leads to placing the groups in defined categories. The
end result of this leads to the synthesis of a system of classification.
ā¢ Kingdom : Plantae Division : Magnoliophyta Class : Asteropsida Order : Asterales
Family : Asteraceae Genus : Helianthus Species : annuusClassification is the
arrangement of organisms into groups having common characteristics. These groups are
then arranged according to a system. For example similar species of flowering plants are
placed into a genus (plural, genera); similar genera are grouped into families; families
with common features are arranged into orders, orders into classes and classes into
divisions. Classification results in the placing of organisms into a hierarchy of ranks or
categories such as species, genera, and families and so on.Indeed, classification is both,
an information storage and retrieval system without which scientific communication
would be impossible.
15. ACKNOWLEDGEMENT
ā¢ Google for images
ā¢ Advanced Plant Taxonomy by A. K. Mondal
ā¢ A text book of Botany- Hait, Bhattacharya & Ghosh
ā¢ Plant Taxonomy āO. P. Sharma
ā¢ This presentation has been developed for the enrichment of online learning without
any financial interest. The author is grateful for all for having the pleasure of uses of
the content used in this presentation.