Herbarium is the collection of plant specimens arranged in the sequence of an accepted calcification. Plant specimens are dried, pressed and mounted on sheets. Fleshy parts of plants are collected in 4% formalin solution of F.A.A. Herbaria helps in providing correct knowledge of plants through representative specimens. Classification of Bentham and Hooker is followed in Common Wealth Countries including India.
The main objectives of herbaria making are :
The following equipment are used in the preparation of herbaria:
Method for the preparation of herbarium
Plant materials from Pteriodphyta, Gymnosperm and Angiosperms are normally preserved as dried and pressed specimens on herbarium sheets. Infect flowers and fruits should be taken while collecting Angiosperms, because without flowers and fruits identification of plants will be difficult. Therefore, 3 to 4 specimens of the same pants from different localities and different seasons are collected. Students should visit same habitat in different seasons to collect plant specimens. The main step to prepare herbarium sheet are:
Fresh materials are pressed in plant press in herbarium press. Three to four specimens of the same plant should be pressed. If the specimens is large then it should be pressed in "V" or "N" manner. If leaves and flower are crowded on the stem, then flowers and leaves can be detached and pressed on sheet in their natural arrangement. Underground parts should be made dust free before preserving. Aquatic plants should be properly spread in water and then uplifted and pressed carefully. To press fleshy organs, sponge pads should be used.
For drying of specimens, following two methods are used:
This is slightly different from previous method, here previously pressed and dried specimens are kept in drying press at adequate temperature ,water vapourizes and materials gets dried in short duration. Temperature management is important in this method because plants turn brown and brittle at high temperature.
Well – pressed and dried specimens are mounted on 12'' X 18" herbariums sheets with the help of gum or fevicol containing 1% HgCl2 . Sometimes mixture of ethylcellulose and resin or cello-tape is used as mounting media. Holland cloth is also used for fixing specimens. In certain museums specimens are tagged to herbarium sheets with the help of needle and thread. Labeling is done after mounting.
After fixing specimens on herbarium sheet the following information is entered at right side of the lower corner of herbarium sheet.
Properly mounted and labeled herbarium sheets are preserved for future records. Specimens are arranged according to recognized system of classification, i.e. Bentham and Hooker's, Engler and Prantl's system of classification. Indexing should be done for easy operation of herbarium.
The specimens mounted on sheets may be destroyed by beetles, booklouse, drugstore beetles and other insects during storage. This problem may be overcome by fumigation with suitable insecticides. DDT, Lauryl phenyl chlorophenate, carbon tetrachloride and other insecticides may also be sprayed on specimen. Naphthalene balls may also be used as repellent.
By following above methods and steps you would be able to prepare a good herbarium yourselves without any doubt. Please follow above procedure step by step to prepare a good herbarium.
Hakimuddin Kuwakhedawala is based in India with over 15 years experience as a teacher. Teaching and writing are his passion. Most of the articles of Hakimuddin are related to education, exam, environmental problems, etc.
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After reading this article I was reminded about my daughter who prepared a Herbarium a few weeks back and for which we also helped. She was asking many kinds for roots, flowers and leaves and being a green area we got almost all the plants requested by her. She nicely made a folder and gammxin powder was applied to each folder so that the plants wont be attacked and eaten away by the insects and ants. Luckily her project was the best and she got good marks too. There are ready made Herbarium available in the shops with just image cuttings of the plants which is not useful.