Herbarium - Preparation and uses

A herbarium is a store-house of preserved plant collections - a Herbarium Specimen is a pressed and dried plant sample permanently glued/strapped to a sheet of paper, together with a documentation label. Herbaria act as centres for research and as a source of material for systematic work.

Preparing a herbarium specimen (6 steps): (1) Plant collection - field collection, liquid-preserved collection, living collection, or collection for molecular studies, always with flower or fruit present; (2) Documentation of field-site data - date, time, country, state, city, specific locality, latitude, longitude, elevation and landmark information, later typed onto the herbarium label; (3) Preparation of the plant specimen - pressed immediately in the field with a portable plant press, then transferred to a standard 12'x18' plant press secured by straps; (4) Mounting - the specimen is affixed to a standard 29cm x 41cm herbarium sheet with white glue or a methyl cellulose solution; (5) Herbarium labels - typically 4-5' wide and 2-3' tall, recording habit, habitat, vegetation type, landmark information, latitude/longitude, an image, collection number, collection date and the collector's name; (6) Protection against mold and insects - historically 2% mercuric chloride, naphthalene, DDT or carbon disulphide application, or formaldehyde fumigation; today deep-freezing at -20 degrees C is the world-standard method.

The Kew Herbarium (South West London, founded 1840) houses 'the largest and most diverse botanical and mycological collections in the world' - more than 30,000 kinds of living plants, over seven million preserved specimens, a library of over 750,000 volumes and over 175,000 prints/photographs/manuscripts/maps. …