Short note on uses 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.