Herbaria and uses, Importance of Herbaria

Herbaria and their uses

Herbarium is a collection of pressed, dried plant specimens mounted on specified sheets, identified and arranged in the order of an approved and well known system of classification. It also refers to the institution where dried plant specimens are maintained and studied. eg. Herbarium of  Botanical Survey of India, Coimbatore.

A twig with leaves, inflorescence or flowers is collected from shrubs and trees. In the case of herbs, the collected plant specimens should contain both vegetative and reproductive parts. They are dried by keeping them between the folds of old newspapers. It is necessary to change these papers at regular intervals, until the plants are well dried. The plant specimens along with their parts are dried in a plant press (fig.1.2). It consists of two boards with straps, which help in tightening the newspapers with specimens between the boards.

The dried specimens are pasted on the herbarium sheets of standard size 41 cm X 29 cm. The process of attaching dried and pressed plant specimens on herbarium sheets is known as mounting of specimens.

All the mounted specimens are sprayed with fungicide like 0.1% solution of Mercuric chloride. To protect these dried specimens from the attack of the insects, pesticides such as naphthalene and carbon disulphide can be used. The heavy parts of plants such as seeds and fruits are kept in packets and attached to the sheets.

When a new name for a species is suggested, it is the rule that plant specimens of the same should necessarily be deposited in a recognized herbarium. These specimens are called type specimens. The name of the family is always based on type genus. These specimens are most valuable part of herbarium and they are handled with special care. They are stored in fire-proof cabinets.

If the herbarium specimens are handled with special care, they will be in good condition for a long time. Precautions should be taken against attacks of fungi and insects. It is always better to use chemicals, which can repel the insects from herbarium specimens. The herbarium is always accompanied with a label. It carries the information about the botanical name of the plant, name of the family, habit, place and date of collection and name of the person who collected the specimens.

Some Important National and International Herbaria

S.No.    Name of herbarium      Total No. of        

             specimens  

1. Herbarium of Royal Botanical More than  

    Gardens, Kew, London, England.     60,00,000  

2. Herbarium of Indian Botanical         More than  

    Garden, Kolkata, India. 10,00,000  

3. Botanical Survey of India,       More than  

    Coimbatore, Tamil Nadu.        1,90,000    

4. Presidency College Herbarium,         More than  

    Chennai, Tamil Nadu.    10,000       

5. Rapinat Herbarium, Trichy,    More than  

    Tamil Nadu.         12,000       

Importance of herbarium

1.     Herbarium is a source of knowledge about the flora of a region or a locality or a country.

2.     It is a data store in which the information on plants are available.

3.     The type specimens help in the correct identification of plants.

4.     It provides materials for taxonomic and anatomical studies.

5.     Typical pollen characters have been well emphasized in taxonomy.

6.     Morphological characters of the pollen remain unaltered even after storage upto nearly 200 years.

7.     It is very much useful in the study of cytology, structure of DNA, numerical taxonomy, chaemotaxonomy, etc. It acts as a reservoir of gene pool studies.

8.  Because of its importance, several herbaria have been established at the national and international centres.