Class: 11th Notes

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Botany
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Chapter: Living World

Define the following.
➢ Species.
➢ Kingdom.

Species (John Ray 1693):

It is the basic or lowest taxonomic category, which consists of one or more natural populations of individuals that
resemble one another more closely than
individuals of other species, interbreed freely, having distinct genetic setup and are reproductively isolated from others.
e.g., Panthera Leo (Lion), Mangifera indica (Mango), Solanum tuberosum (Potato), Juglans regia (walnut).

Kingdom (Linnaeus 1735):

It is the highest taxonomic category or level of classification. It includes all organisms that share a set of distinguishing
common characters. There are 5 kingdoms in which the living organisms are classified, namely, Animalia, Plantae,
Fungi, Protista, and Monera.
It is observed that the number of common or correlated characters is maximum in lower rank categories. The number
progressively decreases with the rise in rank of category.

Taxonomic Hierarchy:Taxonomic hierarchy is the process of arranging various organisms into successive levels of
the biological classification either in a decreasing or an increasing order from kingdom to species and vice versa.‖ Each
of this level of the hierarchy is called the taxonomic category or rank.
The various categories used in classification of organisms can be arranged in a hierarchy that indicates levels of kinship.
Nearer the categories in hierarchy the greater is the similarity between the organisms.The hierarchical system was
introduced by Linnaeus in the year 1735; however his classification lacked two categories; phyla and families. These
were added later. Hierarchy of major categories is given as under:
➢ Kingdom
➢ Phylum or Division
➢ Class
➢ Order
➢ Family
➢ Genus
➢ Species
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➢ Taxonomic Hierarchy Categories:

The International Botanical Congress has established seven taxonomic categories in which different organisms are
classified. They are also called as Obligate Categories.

Kingdom
Division
Class
Order
Family
Genus
Species

Difference between Taxonomy and Systematics.

Systematics:

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 The term ―systematics‖ has been derived from a Greek word, ―Systema‖ meaning ―Order‖ or ―sequence‖. It was
coined by Carolus Linnaeus (1707-1778). Systematics is the study of identification, classification and inter-relationships
amongst living organisms. Thus systematics is the science of diversity of organisms. Scientists dealing with systematics
are called systematists. G. G. Simpson (1961) considers systematics as the study of diversity of organisms and all their
comparative and evolutionary relationships based on comparative studies of anatomy, ecology, physiology and
biochemistry.
According to him classification is a sub topic of systematic.
Biosystematics or New systematics or Neo systematics:
Biosystematics deals with the variation within a species and its general evolution. It incorporates evidences from
genetics, cytology, anatomy and physiology of an organism. It was coined by Camp and Gilly in the year 1943.

Taxonomy:
Taxonomy is the branch of biology that deals with the systematic grouping of living organisms. It deals with
identification, nomenclature and classification of
organisms.The word ―Taxonomy‖ has been derived from Greek words, ―Taxis‖, meaning ‗arrangement or division‘,
and ―nomos‖ meaning ‗law or method‘. The term taxonomy was coined by de Candolle (1813) in his book, ―Theorie
Elementaire de la Botanique (Theory of Elementary Botany)‖.
A taxon is referred to as a group of organisms classified as a unit. Taxonomy and systematics are complimentary to one
another.
Rules of binomial nomenclature.
Rules for Scientific Names:
The International Code of Botanical Nomenclature (ICBN, 1961) has formulated
following principles or guidelines for naming of plants.
1. Each organism has a distinct scientific name having two words, generic
and specific.
2. The generic and specific words should not have less than three letters or
more than twelve letters.
3. The generic name is written first. It is like a noun. Its first letter is always
capital.
4. The same generic name cannot be given twice in the same kingdom.
Rather, its repetition in the other kingdoms should also be avoided. The
same specific word can be used several times but with different genera.
e.g. Magnifera indica, Spirogyra indica.
5. The specific word or epithet is written after the generic name. It should be
short, simple but can be compound. e.g. Hibiscus rosa- sinensis.
6. The names are derived from Latin language (Latin Homo – man). When
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words are used from other languages, they are Latinised with suitable
ending. E.g. Magnifera indica.
7. Very rarely generic and specific names are the same. E.g., Gorilla gorilla
8. The name of, the discoverer is appended to the two –word scientific name
either in full or abbreviated form.
9. Scientific name is printed in italics and when hand written they are
underlined separately. Exceptions are made when the name is used as a
title of a book, chapter or Para. The name of the discoverer is appended
on roman script without any break or comma, e.g., Homo sapiens-L.
10. Scientific names given prior to 01/05/1753 for plants (Species Plantarum)
and 01/08/1758 for animals (Systema Naturae) are not recognised.
11. When an organism has been given different names by different workers;
the earlier one is given validity. This is called law of priority.
12. Families or sub – families should be named after some prominent genus
e.g., Asteraceae after Aster, Rosaceae after Rosa.

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