The word 'herbarium' (or 'herbaria' in plural) was originally used in reference to a book about medicinal plants. The term was then used by Tournefort (c. 1700) to describe a collection of dried plants. (1) In modern utilization of the term, it refers to a systematic, permanent physical record of a plant's occurrence at a specific time and place. It acts as a repository or collections of preserved plant and fungal specimens and their associated data (description of when, where, and who collected the specimen) with various functions such as to carry out studies of plant classification, identification, distribution and ecology. In other words, it makes plant specimens available out of season (2, 3, 4, 5, 6).
Bridson, D & Forman, L (eds). 1992. The Herbarium Handbook (Revised Edition). Royal Botanic Gardens, Kew.