Herbarium

• Herbarium is a store house of collected plant specimens which are dried, pressed and preserved on herbarium sheets.
• The sheets are systematically arranged according to an accepted system of classification.
• The herbarium sheets contain a label on the right-hand side at the lower corner.
• The label contains the following information: 
• Date and place of the specimen collected o English, local and botanical names of the plant 
• Family
• Collector’s name
• Preparation of Herbarium: 
• Plants with fully grown leaves and complete inflorescence are collected in a metallic vasculum or polythene bags to preserve moisture.
• Plant specimens are then dried by pressing them in newspaper folders. 
• When specimens are partially dehydrated, they are poisoned by using chemicals such as mercuric chloride, DDT or carbon disulphide to prevent them from any microbes.
• Fleshy organs are stored in FAA mixture (formalin, acetic acid, ethyl alcohol and water).
• Dried specimens are then glued on the herbarium sheets. o The standard international size of a herbarium sheet is 41 × 29 cm.
• On the right-hand side, at the lower corner, a label containing all the data is fixed. 
• Fragment packets, i.e. small paper envelops are also attached to the sheet to preserve loose parts such as seeds.
• The sheet is then covered with a polythene bag to avoid tearing of delicate plant parts.
• Then sheets are arranged according to the accepted system of classification. In India, the Bentham–Hooker system is used in which species of the same genus are arranged together.
• Uses of Herbarium: 
• Provides information on the local flora and the flora of other regions o Provides correct and authentic information of unknown plants o Used as a quick referral for taxonomic studies
• Institutes teaching botany have herbaria. Royal Botanical Gardens, Kew, has the largest herbarium.