The specimens, which are then mounted on sheets of stiff white paper, are labeled with all essential data, such as collector, date and place found, description of the plant, elevation, and special habitat conditions.
As a precaution against insect damage, the pressed plant is frozen or poisoned and the case disinfected.
Specimen sheets are stacked in groups by the species to which they belong and placed into a large lightweight folder that is labelled on the bottom edge.
In such cases, specimens preserved in an herbarium can represent the only record of the plant's original distribution.
Environmental scientists make use of such data to track changes in climate and human impact.