Herbarium

A herbarium is defined as a collection of plants that usually have been dried, pressed and preserved on sheets. The sheets are arranged in accordance with any accepted system of classification (usually Bentham and Hooker’s system). The storage of sheets forms a repository for future use. It provides a quick referback system and is quite useful for people involved in taxonomic studies. All institutes leading with botanical studies maintain their herbaria.

History of Herbaria

Majority of the world’s famous herbaria originated from the botanical gardens. The first herbarium was set up at Pisa in Italy by a professor of botany Luca Ghini. His students bound the paper sheets having plant specimens mounted on them into book volumes, and spread the art of herbarium throughout Europe.

Linnaeus started storing the paper sheets with plants mounted on them in piles, a practice followed even today.

Herbarium technique

For  collection of specimens, one has to carry certain simple tools such as digger for digging roots, a scissor for cutting twigs, knife for woody twigs and a pole with hook for collecting parts of tall trees.

Vasculum box and polythene bags are used to temporarily store fresh shoots to avoid loss of moisture and distortions by drying and shrivelling up.

Succulent parts, fruits, tubers, rhizomes are preserved in bottles having FAA (formalin + acetic acid + alcohol). Some of them can also be dried and kept in packets.

The specimens are spread out, in shortest possible time. They are dried by keeping them between the folds of old newspapers. It is necessary to change these papers at regular intervals to avoid fungal growth. Complete specimens with all parts are dried in a plant press. The plant press consists of a set of two boards with straps, which help in tightening the newspaper sheets with specimens between the boards.

The dried specimens are pasted on the herbarium sheets of standard size (29 × 41 cm). Specimens before fixing are kept upside down on paper sheet, glue or adhesive is applied and then they are mounted on the herbarium sheet.

All the pasted specimens are sprayed with fungicides like 0.1% solution of mercuric chloride, pesticides like DDT, naphthalene and carbon disulphide to check the growth of fungi.

There are several floras in India such as Flora of British India (J. D. Hooker), Flora of Delhi (J. K. Maheshwari) and Flora Simlensis (H. Collet).

Major Herbaria

Largest herbaria of the world are at Royal Botanic Gardens, Kew, England (6.5 million specimens) and Museum of Natural history, Paris (6 million specimens). In India, the largest herbarium is at Indian Botanical Garden, Shibpur, Kolkata, called Central National Herbarium (2 million specimens).

Role of herbaria

• Repository of plant specimens
• Safety of type specimens
• Compilation of Flora, Manuals and Monographs
• Identification facility
• Preservation of voucher specimens
• Knowing ecology of different places.