`color{blue} ul(mathtt ("Taxon"))` : It is the basic unit of classification which represents a rank containing a group of organisms with
similar distinctive characters.

`color{green} ✍️ color{green} mathbf("KEY CONCEPT")`

● Classification of organisms involves a `color{violet}"hierarchy"` of steps in which each step represents a rank or category.

● Such category is called `color{violet}"taxonomic category"` as it is a part of overall taxonomic arrangement and all categories together constitute the taxonomic hierarchy.

● Each category, referred to as a `color{violet}"unit of classification"` , represents a `color{violet}"rank"` and is commonly termed as `color{violet}"taxon"` (pl.: taxa).



Eg .:The group represented by insects share common features like three pairs of jointed legs can. It means insects are recognisable concrete objects which can be classified, and thus are given a rank or category.

● These taxonomic groups/ categories are `color{violet}"distinct biological entities"` and not merely morphological aggregates.

● The basic requirement to assign a taxon is the knowledge of characters of an individual or group of organisms. This helps in
identifying similarities and dissimilarities among the individuals of the same kind of organisms as well as of other kinds of organisms.

● Taxonomical studies of all known organisms have led to the development of common categories such as kingdom, phylum or division (for plants), class, order, family, genus and species. These are broad categories, also called `color{violet}"obligate or common categories."`

● All the members of a specific taxonomic category possess features different from those of others.

`color{Brown}"Maximum similarity is observed in the lowest category of each classification ie., Species"`

● However, taxonomists have also developed sub-categories in this hierarchy to facilitate more sound and scientific placement of various taxa. These sub categories are called `color{violet}"Intermediate categories."` These include sub- species( varieties), sub- genus, sub-family, sub-order, sub-class and sub- phyla.

`color{brown}"With the rise in Hierarchy, the similarity among characters decreases"`




`color{purple}♣ color{green} "Mneumonic Aid (for taxonomy order)"`:

`color{violet}"K"`ing `color{violet}"P"`hillip `color{violet}"C"`ame `color{violet}"O"`ver `color{violet}"F"`rom `color{violet}"G"`reat `color{violet}"S"`pain

● `color{blue} ul(mathtt ("Species"))` (coined by `color{violet}"John Ray"` ) is considered the most basic taxonomic category. It is the `color{violet}"lowest"` in the taxonomic hierarchy of any organism.

● Taxonomic studies consider a group of individual organisms with `color{violet}"fundamental similarities"` as a species. The individuals of a population in a species have closer resemblance to each other than to members of other species.

● One species can be distinguished from the other closely related species based on the `color{violet}"distinct morphological differences"`.

Eg., : 𝘔𝘢𝘯𝘨𝘪𝘧𝘦𝘳𝘢 𝘪𝘯𝘥𝘪𝘤𝘢 (mango), 𝘚𝘰𝘭𝘢𝘯𝘶𝘮 𝘵𝘶𝘣𝘦𝘳𝘰𝘴𝘶𝘮 (potato) and 𝘗𝘢𝘯𝘵𝘩𝘦𝘳𝘢 𝘭𝘦𝘰 (lion). All the three names, 𝘪𝘯𝘥𝘪𝘤𝘢, 𝘵𝘶𝘣𝘦𝘳𝘰𝘴𝘶𝘮 and 𝘭𝘦𝘰 represent the specific epithets, while the first words 𝘔𝘢𝘯𝘨𝘪𝘧𝘦𝘳𝘢, 𝘚𝘰𝘭𝘢𝘯𝘶𝘮 and 𝘗𝘢𝘯𝘵𝘩𝘦𝘳𝘢 are genera and represents another higher level of taxon or category.

● Each genus may have one or more than one specific epithets representing different organisms, but having morphological similarities.
Eg., : 𝘗𝘢𝘯𝘵𝘩𝘦𝘳𝘢 has another specific epithet called 𝘵𝘪𝘨𝘳𝘪𝘴 and 𝘚𝘰𝘭𝘢𝘯𝘶𝘮 includes species like 𝘯𝘪𝘨𝘳𝘶𝘮 and 𝘮𝘦𝘭𝘰𝘯𝘨𝘦𝘯𝘢.

● Genus comprises a `color{violet}"group of related species"` which has more characters in common in comparison to species of other genera. Thus genera are aggregates of closely related species.

Eg.,: Lion (𝘗𝘢𝘯𝘵𝘩𝘦𝘳𝘢 leo), leopard (𝘗𝘢𝘯𝘵𝘩𝘦𝘳𝘢 pardus) and tiger (𝘗𝘢𝘯𝘵𝘩𝘦𝘳𝘢 tigris) with several common features, are all species of the genus 𝘗𝘢𝘯𝘵𝘩𝘦𝘳𝘢. This genus differs from another genus 𝘍𝘦𝘭𝘪𝘴 which includes cats.

● Family consist of a group of related genera with less number of similarities as compared to genus and species.

● Families are characterised on the basis of both `color{violet}"vegetative and reproductive features"` of plant species. Among plants for example, three
Eg1 ., : Among plants, different genera 𝘚𝘰𝘭𝘢𝘯𝘶𝘮, 𝘗𝘦𝘵𝘶𝘯𝘪𝘢 and 𝘋𝘢𝘵𝘶𝘳𝘢 are placed in the family Solanaceae.
Eg2., : Among animals, genus 𝘗𝘢𝘯𝘵𝘩𝘦𝘳𝘢 comprising lion, tiger, leopard is put along with genus, 𝘍𝘦𝘭𝘪𝘴 (cats) in the family Felidae

● Members of a plant family end with a suffix- `color{violet}"aeae"`. Members of animal family end with a suffix - `color{violet}"idae"`

● Generally, order and other higher taxonomic categories are identified based on the `color{violet}"aggregates of characters"`.

● Order being a higher category, is the `color{violet}"assemblage of families which exhibit a few similar characters"`. The similar characters are less in number as compared to different genera included in a family.

Eg 1., : Plant families like Convolvulaceae, Solanaceae are included in the order Polymoniales mainly based on the floral characters.
Eg 2., : The animal order, Carnivora, includes families like Felidae and Cancidae

● This category includes related orders.

Eg., order Primata comprising monkey, gorilla and gibbon is placed in class Mammalia along with order Carnivora that includes animals like tiger, cat and dog. Class Mammalia has other orders also.

● It is a taxonomic category higher than class and lower than kingdom.

● It consist of a group of related classes having similar characters.

● The term used for plants is `color{violet}"Division"` and for animals is `color{violet}"Phylum"`.

Eg.,: Phylum Chordata comprises the classes Pisces, Amphibia, Reptilia, Aves and Mammalia, characterised by presence of common features like dorsal hollow nerve chord and notochord.

● It is the `color{violet}"highest category"` in a taxonomical hierarchy.

● This includes a group of different phyla with organisms sharing common distinctive characters.

Eg: All animals belonging to various phyla are assigned to the highest category called `color{violet}"Kingdom Animalia"` in the classification
system of animals.

Eg:: The `color{violet}"Kingdom Plantae"`, on the other hand, is distinct, and comprises all plants from various divisions.

`color { maroon} ® color{maroon} ul ("REMEMBER")`

● `color{blue} ul(mathtt ("Taxonomical Aids"))` :
are the established `color{violet}"procedures and techniques"` to store and preserve the information as well as the specimens for the classiification of all the organisms.

● Taxonomic studies of various species of plants, animals and other organisms are useful in agriculture, forestry, industry and in general in
knowing our bio-resources and their diversity.

●These studies would require `color{violet}"correct classification and identification"` of organisms. Identification of organisms requires `color{violet}"intensive laboratory and field studies"`. The collection of actual specimens of plant and animal species is essential and is the prime source of taxonomic studies.

●Taxonomic aids are also fundamental to `color{violet}"studies and essential for training in systematics"`. It is used for classification of an organism, and the information gathered is also stored along with the specimens. In some cases the specimen is preserved for future studies.

●Some of the taxonomical aids developed by biologists include
`color{brown}"Herbarium, Botanical gardens, Museums, zoological parks, keys"`, etc.

● `color{blue} ul(mathtt ("Herbarium"))` is a store house of
`color{violet}"collected plant specimens that are
dried, pressed and preserved on sheets"`.

●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 `color{violet}"label"` providing information about date and place of collection, English, local and botanical names, family, collector’s name, etc.

● Herbaria also serve as quick referral systems in taxonomical studies.

● These specialised gardens have `color{violet}"collections of living plants"` for reference.

● Plant species in these gardens are grown for `color{violet}"identification purposes"` and each plant is `color{violet}"labelled"` indicating its botanical/scientific name and its family.

●The famous botanical gardens are at

`color{brown}"Kew (England)"`
`color{brown}"Indian Botanical Garden, Howrah (India)"`
`color{brown}"National Botanical Research Institute, Lucknow (India)"`.

● Biological museums are generally set up in educational institutes such as schools and colleges.

● Museums have collections of `color{violet}"preserved plant and animal specimens"` for study and reference. Specimens are preserved
in the containers or jars in `color{violet}"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.

● These are the places where `color{violet}"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.

● `color{blue} ul(mathtt ("Key"))` are a type of analytical taxonomical aid used for identification of plants and animals
based on the `color{violet}"similarities and dissimilarities"`.

● .A biological key is a `color{violet}"list of questions"` that helps to identify and classify plants and animals. Each question presents contrasting characters of an organism in a pair called a `color{violet}"couplet"`.

● To classify the organism, the character `color{violet}"similar to the organism has to be chosen"`. So, in a couplet, one character is accepted and the other is rejected.

● Answering the questions in an analytical manner helps in identifying the organism.

● Separate taxonomic keys are required for each taxonomic category such as family, genus and species, for the purpose of identification.

● `color{blue} ul(mathtt ("Monographs"))` contain a comprehensive systematic study of a particular taxonomic group. It contains information on any `color{violet}"one taxon"`. They try to review all the facts about a taxonomic group including its taxonomic history, morphology, chromosome numbers, pollination, reproductive biology, species concepts etc.

● `color{blue} ul(mathtt ("Flora"))` contains the actual account of habitat and distribution of `color{violet}"plants of a given area"`. These are mostly area `color{violet}"constrained and exhaustive"`. These provide the index to the plant species found in a particular area. These are less comprehensive in scope than a monograph and are often compiled when nomenclature needs clarified or new species are added. They can be taxon- and geography-based. These usually include dichotomous keys for identification purposes and range maps as well.

● `color{blue} ul(mathtt ("Manuals"))` are useful in providing information for identification of `color{violet}"names of species found in an area"`. A manual does not need to be exhaustive and its scope is typically `color{violet}"user defined"`.

● All these are means of recording descriptions and also help in correct identification of the organisms.