Taxonomy:- Taxis = arrangement, nomos = law
This word was proposed by A.P. de. candolle in his book "Theories elementaire de la botanique" (Theory of elementary botany)
(1) Identification:- A process by which an organism is recognised from the other already known organisms and is assigned to a particular taxonomic group is called identification.
(2) Nomenclature:-Naming of organisms according to international specific rules is called nomenclature.
(3) Classification:- a process by which any organisms is grouped into convenient categories on the basis of some easily observable characters.
Systematics :-
The term systematics was given by linnaeus. The word systematics derived from Latin word "systema" which means "systematic arrangement of organisms". Linnaeus used "systema naturae" as a title of his publication.
Systematics includes identification, nomenclature, classification and evolutionary relationship between organisms.
Note :- In modern taxonomical studies, taxonomists use external and internal structure, along with the structure of cell, development process and ecological information of organisms.
(1) Cytotaxonomy :- The use of cytological characters of plants in classification or in solving taxonomic problems is called cytotaxonomy. cytotaxonomy is based on cytological information like chromosome number, structure and behaviour etc.
(2) Chemotaxonomy:- It is based on the chemical constituents of plants.
The basic chemical compounds used in chemotaxonomy are alkaloids, carotenoids, tennis, polysaccharide, nucleic acids, fatty acids, amino acids, aromatic compounds etc.
Some Information:-
• Practical significance of taxonomy is ➡️ Identification of unknown organism.
• Maximum diversity is found in tropical rain forests.
• Second maximum diversity is found in coral reefs.
• The number of species that are known and described range between 1.7 - 1.8 million. This refers to biodiversity or the number and types of organisms present on earth.
Binomial system:-
Given by carolus Linnaeus
Carolus Linnaeus:- Linnaeus used this nomenclature system for the first time on large scale and proposed scientific name of many plants and animals.
•Linnaeus is the founder of bionomial system.
•Linnaeus proposed scientific name of plants in his book "Species plantarum". It was published on 1May 1753. So this was the initiation of binomial system for plants.So any name proposed (for plants) before this date is not accepted today.
•Linnaeus proposed scientific name of animals in his book "Systema naturae" (10th edition).
•This 10th edition of "systema naturae" was published on 1 August 1758. So initiation of binomial system for animals is believed to be started on 1 August 1758.
"International Code Of Botanical Nomenclature"
•Collection of rules regarding scientific nomenclature of plants is known as ICBN.
•ICBN was first accepted in 1961.
Main Rules Of ICBN :-
(1) According to binomial system name of any species consists of two components or words-
(i) Generic Name - Name of genus
(ii) Specific epithet
e.g.
Solanum tuberosum(Potato)
⬇️ ⬇️
Generic name Specific epithet
Mangifera indica(Mango)
⬇️ ⬇️
Generic name Specific epithet
(2) In plant nomenclature (ICBN) tautonyms are not valid i.e. generic name and specific epithet should not be same in plants.
eg. Mangifera indica
But tautonyms are valid in animal nomenclature (ICZN - International Code Of zoological Nomenclature)
eg. Naja Naja (Indian cobra)
Rattus rattus(Rat)
(3) First letter of generic name should be in capital letter and first letter of specific epithet should be in small letter.
eg. Mangifera indica
(4) When written with free hand or typed, then generic name and specific apithet should be separately underline. But during printing name should be in italics to indicate their Latin origin.
(5) Name of scientist (who proposed nomenclature) should be written in short after the specific epithet.
eg. mangifera indica Linn.
(6) Name of scientist should be neither underline nor italics,but written in Roman letters (simple alphabets).
(7) Scientific names should be derived from Latin (usually) or Greek language because they are dead languages.
(8) Type specimen (Herbarium Sheet) of newly discovered plant should be placed in herbarium.
Trinomial system:-
• Proposed by Huxley and Stricklandt
• According to this system name of any organism is composed of three words -
(i) Generic Name
(ii) Specific epithet
(iii) Subspecific epithet(Name of Variety)
eg. Brassica oleracea botrytis (Cauliflower)
Brassica oleracea capitata (Cabbage)
Brassica oleracea caulorapa (knolkhol)
⬇️ ⬇️ ⬇️
Generic name ⬇️ Variety
Specific epithet
Biological classification :-
The art of identifying distinctions among organisms and placing them into groups that reflect their most significant features and relationship is called biological classification.
The purpose of biological classification is to organise and the vast number of known organisms into categories that could be nemed, remembered and studied.
Type Of Biological Classification
(1) Practical Classification:- In this type of classification, plants are classified on the basis of their economic importance or human use.This classification system is the earliest system.
eg.
Oil yielding plants ➡️ Coconut,Walnut, Soyabean
Fibre yielding plants ➡️ Jute,Cotton
Medicinal plants ➡️. Rauwolfia,Cinchona, Eucalyptus
Note: In this classification,any one plant can be a member of more than one group.
eg. Turmeric: Multi uses plant,it gives both medicines and spices.
(2) Artificial Classification:-In this type of classification plants are classified on the basis of one or two morphological characters.i.e. over all morphology is not considered.
In this system equal what is given to both vegetative and reproductive characters.
For e.g.- Classification proposed by Linnaeus is Artificial
Linnaeus classified plant Kingdom on the basis stamen (mainly) into 24 classes.
Note: In the book "Generous plantarum" Linnaeus classified the plant Kingdom into 24 classes on the basis of stamen so, Linnaeus classification is also called sexual classification.
Note:- Linnaeus divided phenerogames (gymnosperm and angiosperms) into 23 classes starting with class monandria with a single stamen (eg. Canna) and plants with twenty or more stamens inserted in Calyx were assigned to class Icosandria. He included other plants such as algae, fungi, mosses (bryophytes) and furns (Pteridophytes) in a separate class called cryptogamia.
(3) Natural classification:-in this type, plants are classified on the basis of their complete (gross) morphological characters of (stem root leaves flowers etc).
Importance -
Natural classification is believed to be the best classification, because it represents the natural similarities and dissimilarities of plants i.e. it represents the inter relationship among plants.
In this classification, the plant belonging to the same group show many similarities, while in artificial classification, the plants belonging to the same group shows only, 1 or 2 similar characters, They have many dissimilarties also.
Natural classification is two types
(a) Natural phylogenetic
(b) Natural non phylogenetic
(a) Natural phylogenetic:- In this classification, both grass morphology and phylogeny are considered.In phylogenetic classification, the plants are arranged on the basis of their evolution.
(b) Natural non phylogenetic:- In this classification, the phylogeny of the plant is not considered i.e. only the grass morphology of the plant is considered.
Lamarck - Proposed the term phylogeny
Charles Darwin - Gave detailed explanation of phylogeny in his book "Origin of Species" (1859) it was most popular book of its time.
Thallophyta ➡️ Bryophyta ➡️ Pteridophyta ➡️ Gymnosperm ➡️ Angiosperm(Most advanced plants)
Note:-Phylogenetic classification is also known as cladistic classification
(4) Phenetic classification or Numerical classification:-
In it plants are classified on the basis of numbers of similarities and dissimilarities. This classification is easily carried out by using computers and it is based on all observable characteristics. In this classification number and codes are assigned to all the characters and the data are prepared and then processed. Those organism which have maximum similarities are placed in same group. In this way each character is given equal importance and at the same time hundreds of characters can be considered.
Note:-
In this classification importance to any one character is not given, all characters have seme importance. While in natural classification floral (reproductive) characters have more importance than vegetative (root, stem and leaves)characters.
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There are 7 main taxonomic categories. They are obligate or essential or broad categories i.e. they are strictly used at the time of any plant classification.
There are some extra or sub categories, like sub division, sub order, sub family etc. They are used only when they are needed.
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• The classification of any plant or animal is a written in descending order.
• Hierarchy - descending or ascending arrangement of taxonomic categories is known as hierarchy.
• Species - Smallest taxonomic category and basic unit of classification.
Note:-
As we go higher from species to Kingdom, number of common characters decreases. Lower the taxa more are the characteristics that the member with in the taxon share. Higher the category, greater is the difficulty of determining the relationship to other taxa at the same level.
Suffix For Taxa(Taxon)
Note:- There is no suffix For Genus,Species and Kingdom
Classification is not a single step process but involves hierarchy of steps in which each step represents a rank or category since the category is a part of overall taxonomic arrangement, it is called the taxonomic category and all categories together constitute the taxonomic hierarchy.Each category referred to as a unit of classification, infact, represents a rank and is commonly termed as taxon (PI...taxa)
Species:- Taxonomic studies consider a group of individual organism with fundamental similarities as species.One should be able to distinguish one species from the other closely related species based on the distinct morphological difference.
Genus:- Genus comprises a group of related species which has more characters in common in comparison to species of other genera.Each genus may have one or more than one specific epithet representing different organisms, but having morphological similarities.
For example:- Solanum tuberosum (potato), solanum melongena (brinjal) and solanum nigrum (makoi) are three different but related species.Hence they all belong to the Same genus solanum.
Family:- Family has a group of related genera with still less number of similarities as compared to genus and species. Families are characterised on the basis of both vegetative and reproductive features of plant species but reproductive or sexual or floral characters are used mainly.
For example:- Three different genera solanum, Petunia and Datura are included in family solanaceae.
Order:-Order has a group of related families with still less number of similarities as compare to family, genus and species. Order being a higher category is the assemblage of families which exhibit a few similar characters only.
For example:-Plant families like convolvulaceae, Solanaceae are included in the order Polymoniales mainly based on the floral or reproductive or sexual characters.
Class:- Class includes organisms of related orders having less similarities than orders.
Division:- Division includes all organisms belonging to different classes having a few common characters.
Note:- Order and other higher taxonomic categories are identified on the basis of aggregates of characters.
Biologists have established certain procedures and techniques to store and preserve the information as well as the specimens. some of these are explained to help you understand the usage of these aids.
(1) Herbarium/Dry garden:-Herbarium is a store house of collected plant specimens that are dried, pressed and preserved on sheet. Standard size of herbarium sheet is 11.5×16.5 inches. Further, these sheets are arranged according to a universally accepted system of classification. These specimens, along with their descriptions on herbarium sheets, become a store house or repository for future use. The herbarium sheets also carry a lebel providing information about date and place of collection, English, local and botanical names, family, collector's name etc. Herberia also serve as quick referral systems in taxonomical studies.
(2) Botanical Gardens:- These specialised gardens have collections of living plants for reference. Plant species in these gardens are grown for identification purposes and each plant is labelled indicating its Botanical/ scientific name and its family. The famous botanical gardens are at Kew (England), Indian Botanical garden, Howrah (India) and at National Botanical research institute, Lucknow (India).
(3) Museum:- Biological museums are generally set up in educational institutes such as schools and colleges. Museums have collections of preserved plant and animal specimens for study and reference. Specimens are preserved in the containers or jars in preservative solutions. Plant and animal specimens may also be preserved as dry specimens. Insects are preserved in insect boxes after collecting, killing and pinning. Larger animals like birds and mammals are usually stuffed and preserved. Museums often have collections of skeletons of animals too.
(4) Zoological parks:- These are the pleces where wild animals are kept in protected environments under human care and which enable us to learn about their food habits and behaviour. All animals in a zoo are provided, as far as possible, the conditions similar to their natural habitats. Children love visiting these parks, commonly called zoos.
(5) Key:- key is used for identification of plants and animals based on the similarities and dissimilarities.
• The keys are based on the contrasting characters generally in a pair called couplet. It represents the choice made between the two opposite options. This results in acceptance of only one and rejection of the other.
• Separate taxonomic keys are required for each taxonomic category such as family, genus and species for identification purpose.
• Each statement of couplet in the key is called a lead.
• Keys are generally analytical in nature.
Catalogue:- It is a small booklet which gives amount for books related to botanical titles, full name of authors and their publication.
Flora:- It contains the index, name and actual account of habitat and distribution of plants of a particular area.
Manuals:- They are useful in providing information for identification of names of species found in an area.
Monographs:- They contain information on any one taxon.
John Ray:- Proposed the term and concept of species. He described more than 18 thousands plants and animals in his book Historia generalis plantarum.
Biological concept of species:-
(1) Ernst Mayr(Darwin of 20th century) proposed the biological concept of species.
(2) Mayr defined the "species" in the form of biological concept.
(3) According to Mayr "All the members that can interbreed among themself and can produce fertile offsprings are the members of same species"
But this definition of Mayr was incomplete because this definition is applicable to sexual reproducing living beings because there are many organisms that have only asexual mode of reproduction.
eg. Bacteria, Mycoplasma,BGA
(4) The main character in determination of any species is interbreeding. But this character is not used in taxonomy. In taxonomy, the determination of species is mainly based on morphological characters.
Taxonomy concept of species:-
When the species is determined on the basis of morphological characters then it is called as taxonomy species.
eg. If two plants have almost Same fundamental morphological characters, then they belong to same species.
Brassica oleracea
⬇️
⬇️
-----------------------------⬇️---------------------
⬇️ ⬇️ ⬇️
⬇️ Cabbage ⬇️
Cauliflower knol-khol
These 3 have same morphological characters. Therefore they belong to same taxonomic species i.e. one taxonomic species.
• In higher plants, the determination of species is mainly based on the morphology of flower (floral morphology). Because floral (reproductive) characters are more conservative as compared to vegetative (Root, Stem, Leaf) characters i.e. they do not show major changes.
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