Used of Herbarium.

After 24 hours the sheets are changed. Blotting papers can be used. They help in quick drying. Two or three changes are required  at an interval of 3-5 days for complete drying of the specimens . Some workers prefer to maintain the specimens in drying sheets for 1 - 2 months. Meanwhile herbarium sheets are selected. They are available in different colors. The general size is 30 × 45 cm. It is slightly shorted Shorter in American herbaria. Good quality glue is applied to the back of dried specimen and the same is placed over the herbarium sheet. Students prefer to use cellotape but the same should be avoided as its retaining power is little. Labels are fixed over the lower right hand corner of the sheets. Information about the family, Genus species author, Plant characteristics, area, date and collector’s  name is given over each label. The sheets are now covered with polythene or tissue paper in order to avoid tearing of delicate parts. Heavy parts like fruits or seeds are kept in a paper or polythene packet and attached to the sheet. Herbarium sheets are arranged according to a system of classification, E, g., Bentham and Hooker in India. The specimens belonging to the same genus are often packed together and placed in steel cabinets. The specimens are treated with 0.1 % mercuric chloride for preventing fungal attack. DDT, naphthalene and carbon disulphide are also used as pesticide . Repelling chemicals are placed alongwith herbarium sheets for protection against insects.

Used of Herbarium. It provides information about the local flora as well as flora of distant areas. Herbaria are used for correct and authentic identification of unknown plats. It provides  information about the ecology of different placed. The information is useful in locating wild varieties and relatives of economically varieties. IT depicts the morphological variations found in species. Information is obtained as to the season of flowering of various plants. It serves as a quick referral system for taxonomic studies.

Name                                                                                           Number of Herbarium Specimens

1.       Royal Botanical Gardens, Kew                                        6.5 million

2.       Museum of Natural History                                            Over 6.0 million

3.       Conservatoire at Jardical Botaniques de Geneve        Over 5.0 million

4.       V.L. Komarov Botanical Institute of Azerbaijan            4.0 million

5.       New York Botanical Garden                                            4.0 million

6.       Central National Herbarium Sibpur Kolkata India       2.0 million

7.       Madras Herbarium, Coimbatore India                           150000

8.       Herbarium of National Botanical Research Institute   80000

Lucknow India.

        

Identification of Species

Manuals. floras monographs, catalogues and keys are used in identification of species Manual. It is handy book containing instruction as to occurrence, collection and identification of species found in a particular area.

Flora. It is book containing information as to the habitat, climate, seasonal changes distribution, description and index of plans found in a specific area.

Monograph. It is treatise having all information about a particular taxon like family or genus.

Catalogue. It is list or register that enumerates methodically all the species found in a particular place often with brief description aiding identification.

Key. It is booklet containing list of characters and their alternates which are helpful in identification of various taxa – class, order, family, genus and species