Living organisms are classified because
(i) There are millions of organisms on the earth. which
need a proper system of classification for their easy
identification and methodical studies
(ii) A numlkr of new organisms are discovered each
year. They require a particular system to be identified
and to find out their correct position in a group.

TAXONOMICAL AIDS
Taxonomical aids are techniques and procedures to store
information as well as specimens or identification and
classification of organisms.
The taxonomic studies of various plants, animals and other
organisms are useful in areas like agriculture, forestry,
industry and knowing our bioresources and their diversity.
All these studies need correct identification and classification
of organisms.
Identification of organisms requires intensive laboratory
and field studies. The collection of actual specimens of
plants and animal species, knowing their habitats and other
traits are essential and are the prime source of taxonomic
studies. All this information is used in classification of an
organism and is also stored along with the specimens.
Sometimes, specimens are also preserved for future studies.
Certain procedures and techniques have been developed to
store and preserve the information as well as the specimens.
Some of these taxonomical aids developed by biologists
include herbarium, botanical gardens, museum, zoological
parks, key, etc.

1. Herbarium
Herbarium (Pl. Herbaria) is a store house of collected plant
specimens that are dried, pressed and preserved on sheets.
These sheets are arranged further according to a universally
accepted system of classification. The institutes and
universities maintain their own herbaria by collecting
specimens from local and far away places.

Preparation of Herbarium
The preparation of herbarium involves following steps
l. The first step is to collect samples of plants.
Different plant parts are collected with the help of
various tools such as scissors, cutters, pruning knife,
digger (khurpi), etc.

2. These collected specimens are carried in a box
vasculum to prevent loss of moisture.
3. The information about the habitat, season, date and
time of collection is also noted neatly in a separate
notebook.
4. Drying of the samples is done by spreading them out
and keeping them between the folds of old
newspapers. Further drying is done in a plant press.
5. Now, the dried specimens are documented on the
herbarium sheets in the following way
(i) The specimen is pasted on a thick sheet (like chart
paper) 29 x 41.5 cm, with the help of glue or other
adhesive.
(ii) Small packets containing seeds or flower samples
are attached to the paper sheet.
(iii) A printed label giving the following information is
pasted on the lower right corner of herbarium
sheet. The label should have the following
information
(a) Name of institution
(b) Scientific name of plant
(c) Common name of plant
(d) Family to which the plant belongs
(e) Region of collection
(f) Date of collection
(g) Name of collector
6. Such herbarium sheets are stored in insect and
dustproof herbarium cabinets.
7. A separate register is maintained to locate the
desired specimen when required. It contains an
alphabetically arranged list of all the genera in the
herbarium.

There is also an organisation called Botanical Survey of
India, headquartered at Kolkata, for exploring the plant
wealth of the country.
Uses of Herbaria
The uses of herbaria are listed below
(i) These are used for identification of plants.
(ii) Compilation of floras, monographs and manuals are
mainly based on the specimens in herbaria.
(iii) Herbaria are useful in locating wild varieties and
relatives of economically important plants.
(iv) They help in knowing the morphological variations
found in species.
(v) Herbaria are useful for research in plant taxonomy,
morphology, ecological distribution, endangered and
rare species, etc.

2. Botanical Gardens
Botanical gardens are specialised gardens that have
collections of living plants for reference. Usually, the
plants specific to the physical conditions of a specific
geographical region are grown in botanical gardens. These
gardens generally have facilities like library, laboratory,
herbarium and museum. The botanical gardens are
maintained by government, semi-government and other
private organisations. Botanists and gardeners look after
•ants in botanical gardens.
Role of Botanical Gardens
A botanical garden has following important roles
(i) Botanical gardens have aesthetic appeal and provide
recreation facility to people.
(ii) A wide variety of plant species grow there, so they
provide ready material for research.
(iii) These gardens also play an important role in
conservation of endangered plant species and genetic
diversity.
(iv) There are more than 500 botanical gardens all over
the world. These provide free exchange of seeds.
(v) These improve the environment, provide greenery,
help in creating pollution-free environment and
some serves as habitat for animals.

3. Museums
Museum is a place for collection of preserved plants and
animal specimens for study and reference. The universities
and educational institutes maintain their own museums in
their botany and zoologv departments. Plants which cannot
be kept in herbaria are preserved in museums, e.g., algae,
fungi, mosses, ferns, fruits, etc. Specimens are preserve in
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 while, the larger animals are either stuffed or
preserved in skeletal forms.

4. Zoological Parks
Zoological parks or zoos are the places where wild animals
are kept in protected environments under human care and
which enable us to learn about their food habits and
behaviour. Zoological parks provide natural habitat to the
animals.
In India there are about 200 zoological parks. These zoos
are managed by the Central Zoo Authority of India. The
World Zoo Conservation Strategy (WZCS) refers to all
these zoological institutions as zoos.
Role of Zoological Parks
(i) Zoos are the centres for conser:vation of threatened
and rare animal species.
(ii) These provide sites for ex situ conservation through
captive breeding of endangered animals.
(iii) The zoological parks increase the public interest in
an understanding of wildlife.
(iv) These are the centres for recreation and education.4. Zoological Parks
Zoological parks or zoos are the places where wild animals
are kept in protected environments under human care and
which enable us to learn about their food habits and
behaviour. Zoological parks provide natural habitat to the
animals.
In India there are about 200 zoological parks. These zoos
are managed by the Central Zoo Authority of India. The
World Zoo Conservation Strategy (WZCS) refers to all
these zoological institutions as zoos.
Role of Zoological Parks
(i) Zoos are the centres for conservation of threatened
and rare animal species.
(ii) These provide sites for ex situ conservation through
captive breeding of endangered animals.
(iii) The zoological parks increase the public interest in
an understanding of wildlife.
(iv) These are the centres for recreation and education.

5. Key
Key is also a taxonomical aid used for identification of
plants and animals based on the similarities and
dissimilarities.
It helps in the identification of plants and animals by
selecting and eliminating the characters according to their
presence or absence in the organism under study.
The keys generally use a pair of two contrasting characters
called couplet. This results in acceptance of one character
that is present in an organism and rejection of the other that
is absent in the organism. Each statement in the key is called
a lead.
There are separate taxonomic keys for each taxonomic
category. These are generally analytical in nature.
The taxonomic keys are of two types
Indented Key
The indented key or yoked key provides a sequence of
choices between two or more characteristics. By careful
selection of characters at each sub-division, the exact name
of the organism can be arrived at.
Bracketed Key
The bracketed key also uses contrasting characters like the
indented key. But in this, these characters are not separated
by intervening sub-dividing characters. Each character in
this case is given a number in brackets.