TAXONOMICAL AIDS 

The laboratory and field studies are required for identification of various species and their placement in taxonomical hierarchy. 

The information thus gathered about the species, needs to be stored for future use. 

The taxonomical aids developed by biologists have established certain procedures and techniques to store and preserve the information as well as the specimens. 

1. Botanical Gardens 

From the time of Theophrastus, gardens have contributed to the science of botany. But, there was an impetus to the botanical explorations only in the Post-Linnean period. 

In ancient Indian culture, cultivation of food and medicinal plants is known since 4000 to 2000 B.C. The 'Hanging Gardens of Babylon' are amongst the wonders of the ancient world. 

During the Middle Ages, from A.D. 600-1600, there was a lapse in learning and introduction of plants. 

In the seventeenth century, there was a revival in the interest and by eighteenth century, most of the famous Botanical Gardens known today had already been established. 

    The functions of a botanical garden are: 

1.    Provide records of local flora for monographic work. 

2.    Provide facilities for collections and identification of living plant material for biosystematic studies / references. 

3.    Supply seeds and material for botanical investigations. 

4.    Botanical gardens have an aesthetic appeal and attract a large number of visitors for observing general plant diversity. 

5.    Provides means of ex-situ conservation strategies. 
        There are about 525 botanical gardens in various countries, but only about 125 have documented collections of authenticated taxa. 
6.    The International Association of Botanical Gardens was established in 1962. This association has published the International Directory of Botanical Gardens (1983). 

Concept Builder

Some of the important Botanical Gardens are listed below :

1. Royal Botanical Garden, Kew, England : It was founded in 1759 by William Alton, but was officially opened in 1841 and was called the Botanical Capital of the World. Sir J.D. Hooker was one of its directors. It is famous for its Alpine house, Rose Garden, Green house, Temperature house, Bamboo garden and Lily pond. It is associated with Jodrell laboratory of experimental taxonomy. It is spread in 200 acres. It is famous for collection of Acacias, Acer, Rhus, Citrus, Rosa, Prunus, Magnolia. It has Chelsa Physic Garden for horticulturists. Kew

2. Orto Botanico (Padua Gardens), Italy: It is said to be the first botanical garden. It is famous for collections of grasses, Alliums, Irids, Paeonias, succulents and hydrophytes.

3. Pisa, Italy: Almost as old as Padua Gardens, it was the first to introduce palaeontological practises; for the study of plants fossils. It is known for trees like Magnolia grandiflora, Liriodendron tulipifera etc. Caesalpino and John Ray have been associated with this garden.

4. Villa Taranto, Italy: It is the most beautiful garden of Italy and important from the horticultural study point of view.

5. Main Botanical Garden, Moscow: Largest Botanical Garden, spread over an area of 900 acres.

BOTANICAL GARDENS OF INDIA

The Indian Botanical Garden, Kolkata, India: It was founded in 1787, by Lt.Col. Robert Kyd. It covers an area of 273 acres and contains collections of world's tropical plants.

It is one of the greatest botanical gardens of the world and one of the first to be established in tropics.

William Roxburgh, 'Father of Indian Botany' was its director from 1793 to 1813.

It has the largest herbarium of east and is famous for the Great Banyan tree, Ficus benghalensis, which is two centuries old, the palm houses, nurseries and the Amazon lily, Victoria amazonica (Nymphaeaceae), the plant with the largest leaves.

It is now under control of BSI (Botanical Survey of India).

Other botanical gardens of India are -

Lloyd Botanical Garden                – Darjeeling
National Botanical Garden           – Lucknow
Lalbag Gardens                           – Bangalore
Saharanpur Botanical Gardens   – Saharanpur

Herbarium (Dry Garden)

It is defined as "a store house of collected plant specimens that are dried, pressed and preserved on sheets."

These sheets are arranged in the sequence of an accepted classification system.

These specimens, along with their description on herbarium sheets, become a store house or repository for future use. The herbarium sheet contains a label on the right-hand side at lower corner.

Label provides 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.

Concept Builder

Herbarium Technique 
The herbarium technique involves the following steps: 

  • (a) Collection    
  • (b) Drying    
  • (c) Poisoning    
  • (d) Mounting      
  • (e) Stitching     
  • (f) Labelling    
  • (g) Deposition 

(a)    Collection: Collection of plant material is done with an aesthetic sense and scientific mind. 
The material should be perfect and complete for determination, i.e., must have fully grown 
leaves, complete inflorescence etc. 
Woody elements are well represented by flowering twigs with 30-40 cm in lengths, while 
herbaceous plants are collected alongwith underground parts. 
Diseased plants, infected twigs should be avoided. 
The collections are kept inside metallic vasculum or polythene bags. 

(b)     Drying: The plant collections are pressed in ordinary newspaper folders, avoiding overlapping. The folders, in turn, are pressed in a field press. The moistened folders are changed frequently to avoid blackening and decay of plant material. 

(c)     Poisoning: The specimens are poisoned to keep away the microbes. When the specimens are partially dehydrated, they are poisoned by using chemicals like 0.1% of corrosive, sublimate (HgCl2).

(d-f)     Mounting, Stitching and Labelling : Dried specimens are glued and stitched on herbarium sheets made up of thick card sheets cut to the required size. The international size of the herbarium sheet is 41× 29 cm (16  ×11  inches) . The field data is entered on label on the right hand side lower corner of the herbarium sheet. Size of label is commonly 7 × 12cm. The small paper envelopes called fragment packets are often attached to the herbarium sheet to hold seeds, extra flowers or loose plant parts. 

(g)    Deposition: Arrangement of specimen, according to accepted classification, is called deposition. In India, herbaria are arranged according to Bentham and Hooker system of classification. 
The specimens so preserved are sprayed with repellents or disinfectants such as DDT powder, copper sulphate solution at intervals of 4 to 6 months to keep off small insect pests such as silver fish. 

Functions of a Herbarium 

The two primary functions of herbarium are accurate identification and alpha taxonomic research (based on gross morphology). 

The secondary functions include closer interaction between the student of general systematics and the herbarium. 

Other important functions of a herbarium are 

1.  To preserve plant wealth including type material and palaeobotanical collections. 

2.  To carry out exchange and loan of preserved plant material for research, exhibitions etc. 
A list of important herbaria of the world is given below along with their standard abbreviations and the approximate number of specimens they hold 
1.Royal Botanical Gardens, Kew (K)         over 6,000,000
4. Central National Herbarium, Calcutta (CAL)       2,000,000 

TYPE SPECIMEN (HERBARIUM SHEET)

Type specimen (Herbarium Sheet) of newly discovered plant should be place in herbarium (Dry garden). Standered size of herbarium sheet is 11.5 × 16.5 inches.

Holotype - Herbarium sheet on which the first description of plant is based.

Isotype - Duplicate of holotype - In presence of holotype a second herbarium sheet prepared from the original plant is called isotype.

Paratype - Additional herbarium sheet used in the first description of plant is called paratype. It is prepared from some other plant of same species having some variations.

Lectotype - In case of holotype is lost, second herbarium sheet prepared from the original plant is called lectotype.

Neotype - In case of holotype and original plant is lost, then herbarium sheet prepared from some other plant of same species is called neotype.

Syntype - In case of holotype and original plant is lost then many herbarium sheet prepared from many plants of same species is called syntype.

Note : Nomenclature is invalid in absence of Herbarium sheet.

3. Keys [Given by John Ray] 

The scheme for identification of plants and animals based upon similarities and dissimilarities is known as a key. It is based on the set of contrasting characters known as couplet, each character of couplet is called as lead. Separate taxonomic keys are required for each taxonomic category. Keys are generally analytical in nature and are of two types (1) Indented key (2) Bracketed key –
1. Indented Key: It has a sequence of choice between two or more statements of characters of species. These require great taxonomic skills to prepare, so are generally less followed. 
2 Bracketed Key: In the Bracketed key the pairs of contrasting statements are used for identification. The bracketed number on the right side indicates the next choice of paired contrasting statements. These are most popular keys. 

4. Zoological Parks

Zoos or zoological gardens (parks) are protected areas or enclosed space where live wild animals are kept, under human care. This enables us to learn their food habits and behaviour.

Objectives are public exhibition to understand wild life, recreation, education, ex situ conservation and breeding of rare fauna.

Largest zoo of the world is situated in Kruger (S. Africa).

National Zoological Park (Delhi) is one of the finest zoo of Asia.

5. Museums

These have collections of preserved plants and animals for study and reference.

Specimens are preserved in jars or containers in preservative solution.

Plant and animal specimens may also be preserved as dry specimens.

Insects are preserved in insect boxes after collecting, killing and pinning.

Larger animals are usually stuffed and preserved.

These often have collections of skeletons of animals too.

Museums are prepared to preserve algae, fungi, mosses, ferns and organs of gymnosperms since they cannot be kept in herbaria. These differs from parks because no living object is displayed in museums.

Some important Museums: 

(i) Natural History Museum, London (England) 

(ii) United States National Museum, Washington 

(iii) National Museum of Natural History (NMNH), Delhi 

(iv) Prince of Wales Museum, Mumbai etc.
Comperative Study of Botanical Garden, Herbarium and Museum : 

6.Flora, Manuals, Monographs and Catalogues 

Flora: Contains the actual account of habitat and distribution of plants of a given area. These provide the index to the plant species found in a particular area. 
Some important flora are given below: 

(i) Flora of British India by J.D. Hooker. 

(ii) Flora of Delhi by J.K. Maheshwari. 

(iii) Flora Indica by William Roxburgh. 

(iv) Flora Simlensis by H. Collet 

Manuals: The complete listing and description of the plants growing in a particular area. 
e.g., Manual of Cultivated Plants by L.H. Bailey 

 Monographs: Contain information on anyone taxon. 
e.g., The Genus Pinus by N.T. Mirov 

Catalogues: This includes the alphabetical arrangements of species describing their features.

Concept Builder

1.    Ex-situ / Off-site conservation strategies for organisms includes Botanical gardens and Zoological parks. 

2.    Succulent plants or those plants which are unsuitable for pressing and drying techniques, are fixed in suitable liquid preservative like 2.5% solution of formaldehyde, glacial acetic acid and ethyl alcohol [FAA]. 

3.    Herbarium technique was first introduced by Caesalpino et. al. 

4.    Botanical gardens of world have 15% or 35,000 plants species of the world flora.
Tapiary -Beautifying areas 
Bonsai trees -Dwarf trees are grown,in pots 

5.    According to WZCS (World Zoo Conservation Strategies), zoological parks are meant to conserve the species that are particularly endangered in their natural environment. India has about 200 zoological parks. 

 

SUMMARY
1.    The living world is rich in variety. Millions of plants and animals have been identified and described but a large number still remains unknown. 

2.    The very range of organisms in terms of size, colour, habitat, physiological and morphological features make us seek the defining characteristics of living organisms. 

3.    In order to facilitate the study of kinds and diversity of organisms, biologists have evolved certain rules and principles for identification, nomenclature and classification of organisms. 

4.    The branch of science dealing with these aspects is referred to as taxonomy. 

5.    The taxonomic studies of various species of plants and animals are useful in agriculture, forestry, industry and in general for knowing our bio-resources and their diversity. 

6.    The basics of taxonomy like identification, naming and classification of organisms are universally evolved under international codes. 

7.    Based on the resemblances and distinct differences, each organism is identified and assigned a correct scientific/biological name comprising two words as per the binomial system of nomenclature. 

8.    An organism represents/occupies a place or position in the system of classification. There are . many categories/ranks and are generally referred to as taxonomic categories or taxa. All the categories constitute a taxonomic hierarchy. 

9.     The basis of modern taxonomic studies is : External and internal structure, along with the structure of cell, development process and ecological information of organisms 

10.     Taxonomists have developed a variety of taxonomic aids to facilitate identification, naming and classification of organisms. These studies are carried out from the actual specimens which are collected from the field and preserved as referrals in the form of herbaria, museums and in botanical gardens and zoological parks. It requires special techniques for collection and preservation of specimens in herbaria and museums. 

11.     Live specimens, on the other hand, of plants and animals, are found in botanical gardens or in zoological parks. 

12.     Taxonomists also prepare and disseminate information through manuals and monographs for further taxonomic studies. 

13.     Taxonomic keys are tools that help in identification based on characteristics.