The Living World - Taxonomical Aids

Description:

Techniques, procedures and stored information that are useful in identification and classification of organisms are called taxonomic aids.

Place where dried and pressed plant specimens are kept is known as herbarium.

Method of herbarium preparation

Field visit and specimen collection −

• An area is selected for botanical excursion.
• For herbaceous plants the entire plant with intact parts is collected.
• For other plants, shoots having flowers, fruits, leaves are selected and cut with the help of a pruning knife.

Pressing and drying −

• Collected specimens are spread over magazine or newspaper sheets.
• Magazine or newspapers are now put inside the press.

Mounting −

• Herbarium sheets are selected.
• Glue is applied to the back of the dried specimen and the same is placed over the herbarium sheets.
• The sheets are covered with polythene or tissue paper in order to avoid tearing of delicate parts.

Labelling −

• Information about the family, genus, species, author, plant characteristics, area, date and collectors name is given over each label.

Preservation −

• Specimens are treated with 0.1% mercuric chloride to prevent fungal attack.
• DDT, naphthalene and carbon disulphide are also used as pesticides.

Important herbaria

• Royal Botanical Gardens, Kew (London) – 6.5 million specimens
• Museum of Natural History (Paris) – over 6 million specimens
• Central National Herbarium (Indian Botanical Gardens) Sibpur, Kolkata, India – 2 million specimens
• Madras Herbarium, Coimbatore India – 1,50,000 specimens