A HERBARIUM IS A COLLECTION OF PLANTS, WHICH HAVE DRIED, PRESSED, MOUNTED ON HERBARIUM SHEETS, IDENTIFIED & CLASSIFIED ACCORDING TO SOME APPROVED SYSTEM OF CLASSIFICATION Luca Ghini initiated the art of herbarium making by pressing and sewing specimens on sheets of paper
1. Digger/Trowel & Pruning Knife/Shear
2. Vasculum Container-useful for handling & keeping the specimens fresh before pressing them. 3. Field Notebook
4. Plant Press & Folders
HERBARIUM TECHNIQUES It involves a series of operations, such as collection, pressing, drying and poisoning, mounting and stitching, labelling, filling and deposition.
Plant specimen should bear flowers and fruits, if present.
Herbaceous small plant specimen should be collected with roots or other underground parts.
A twig of about 25cm with leaves & flowers, will form an ideal material.
Note sheet’s no. & data recorded in the field notebook
Soon after the specimens are collected, they should be pressed in the field itself.
PRESSING Specimens should be carefully placed in the centre on the pressing sheets. If specimens are large enough, they should be bent giving them shape of V, N or W. The bundles should be uniform in thickness in the middle & on the sides. Specimens should be kept one above the other.
DRYING AND POISONING For effective drying, drying papers are replaced by fresh ones. Changing of papers is repeated everyday for about fortnight, or until the plant specimens appear perfectly dried. In the humid climate, the changing of papers is done twice a day to have good results. Artificial heat may be given if the weather is too humid.
MOUNTING AND STITCHING The standard size of a herbarium sheet is 29 x42 cm . They are usually made of durable card sheets. The dried specimens are glued on herbarium sheets and the stem/branches can be stitched/glued with cellophane tapes. It is advisable to mount one specimen on each herbarium sheet. Dissected & loose parts, such as flowers, fruits & seeds, are kept in paper packets & pasted to the mounted sheet.
Name of organization with which specimen plant originated.
Name of the family
Botanical name of the plant
Locality of collection
Date of collection
Habitat of the plant
Field notes & collection no.
Name of collector
FILLING AND STORING
Plant specimens, which have been properly mounted & identified, are filled systematically in special wooden/steel cabinets.
The herbarium sheets loaded with specimens are filed inside folders which are of various colour schemes indicating species, genus, family, geographical area, etc.
Plants are arranged & stored following Bentham & Hooker’s / Engler & Prantl’s system of classification.
A periodical fumigation with chemicals & repoisoning them by brushing with solution of HgCl 2 & using insect repellents would save the herbarium from damage & check the loss of valuable plants.
ROLE OF HERBARIUM
To act as a repository of dried plant specimens, safeguard them against loss & destruction by fungi, insects, etc. & make them available for study .
Several herbaria of repute, keep Type Specimens-the principal proof of the existence of a species, in safe custody, often in rooms with restricted access.
As original documents upon which knowledge of taxonomic characters rests, herbarium specimens greatly help in developing floras, manuals & monographs.
Those engaged in taxonomic studies, can personally identify their engaged collection by comparison with already identified herbarium specimens.
Voucher specimens preserved in various herbaria, provide an index of specimens on which studies on chromosomes, phytochemistry, ultrastructure micro-morphology, etc. have been undertaken .
Most herbaria have specimens collected from different parts of the world &, thus their scrutiny can provide information on the geographical distribution of taxa.