In the case of small herbaceous plants, the entire plant may be preserved. For obvious reasons, only representative portions of larger plants such as trees and shrubs are used. In order to prepare an herbarium specimen, the fresh plant specimen is placed in folded newspaper, flattened in a plant press, and then dried with warm air. Insect pests are controlled by freezing specimens and placing insect repellant in herbarium cases. In order to prevent infestations of damaging insect and fungal pests, climate in the herbarium should be hostile to such organisms.
Plants have an enormous impact on our lives.
In addition to providing virtually all food energy for the biological world through photosynthesis, plants are important sources of drugs, building materials, and fibers for manufacture of paper. Many plants have aesthetic value as ornamentals and, thus, improve the quality of our lives. Weeds and poisonous plants affect us negatively. Herbarium collections document the flora of a region or variation and distribution of particular plant groups. Specimens housed in the herbarium provide documentation about the distributions of native and naturalized plant species from our region, including data on rare, threatened and endangered species and weeds or other kinds of plants of actual or potential economic importance.