Term:

Voucher
Definition:

A herbarium specimen used to document the identification of a species of plant in floristic, monographic, anatomical, ecological, economic, medicinal, taxonomic, etc. studies. If a voucher does not document plant studies there is no way to confirm or reject the identifications of the species in the studies.
Notes:

Boom (1996) defined vouchers as follows: "A voucher specimen is one that serves as proof or supporting evidence for the identity of a particular species or infraspecific entity, and for the existence of that taxon at a certain location at a certain time. It is the ‘anchor’ for all reference to that taxon’s occurrence, and it provides means for checking the identity in the future. In essence, the voucher specimen is the most basic element in plant science research. No matter what the particular field of inquiry—ecology, genetics, systematics, physiology, ethnobotany, pathology, or biodiversity prospecting—if one does not collect a plant specimen and deposit it permanently in an herbarium, then there is no way for any work to be verified as to the identity of the organism involved." Boom, B.M. 1996. Societal and scientific information needs from plant collectors. Pages 16-27 in T. F. Steussey & S. H. Sohmer (eds.), Sampling the green World. Columbia University Press, New York.