Voucher specimens

What is a voucher specimen?

 A 'voucher specimen' is a herbarium specimen used for attesting, authenticating or verifying some information or justifying a conclusion or act. Voucher specimens are almost always a dried herbarium specimen safely stored in a recognized herbarium and serve as a reference material for identification of a plant used in any study, like- morphology, phytochemistry, palynology, anatomy, molecular biology etc. in addition to general taxonomic studies (Radford, 1986; Simpson, 2019).

Why a voucher specimen is needed?

See some examples below:

• Chromosome numbers are very important information for phylogenetic study but this number cannot be guessed just by observing the morphology of a species. Thousand of plant species were studied for counting their chromosome number in mid 20th century but in the lack of any voucher specimen of studied species later on, it became impossible to verify which chromosome number belonged to which species and whether the species was correctly identified or not. Enormous amount of scientific information generated became ambiguous and useless. Had there been voucher specimens preserved in any herbarium the identity of species could have been verified.

• When mycologists started verifying the names of host plants of diseases caused by fungi they found more than 70% of host species misidentified (Funk et al., 2005).

It may happen with any molecular biologist extracting a gene of utility or sequencing any gene from a plant, a phytochemistry worker extracting a very useful chemical compound from a plant, or a medicine man exploring the possibilities of using a plant for treating an ailment. Vouchers tie all experimental results to specific, permanently preserved specimens that can be consulted for correct determination, morphology, locality, ecology, plant and animal associations, and other features. Vouchers are essential for clarifying unexpected results, which may be due to convergence, misinterpretation of morphological or other data, or—perhaps most commonly—misidentification. As such, vouchers are the basis of reproducibility, an essential part of the scientific method. Without a voucher all information generated after a lot of toil may become ambiguous or even useless, experiments cannot be replicated and there is no way to determine if unexpected results are of great biological interest or are due to misidentification.

The following articles explain the importance of voucher specimens:

• Funk et al. (2005) The importance of vouchers

• Culley (2013) Why vouchers matter in botanical research

• Eisenman et al. (2015) Voucher Specimens are Essential for Documenting Source Material Used in Medicinal Plant Investigations

• Turney et al (2015) Non-repeatable science: assessing the frequency of voucher specimen deposition reveals that most arthropod research cannot be verified

• Carter et al. (2017) Preparation and Use of Voucher Specimens for Documenting Research in Weed Science

• Funk et al. (2018) The problem with(out) vouchers

• Buckner et al. (2021) The critical importance of vouchers in genomics

How to prepare a voucher specimen!

If you prefer watching videos to learn, the following short videos can be useful:

Herbarium At Home: A Beginner’s Guide by New York Botanical Garden

RBGE Herbarium: Basic Plant Collecting and Pressing by Royal Botanic Garden Edinburgh. 

OR, just search ‘YouTube’ for ‘how to prepare good herbarium specimens’ and watch any video. 

If you prefer reading, the following text can be useful:

• Live plants need to be dehydrated properly to make them dry and long-lasting as herbarium specimens or voucher specimens. While selecting a plant/ twig for making a herbarium specimen following care should be taken:

• Plant twigs or entire plants should be selected from healthy plants, it should be a good representative of plant morphology and should have an approximate size of 30- 50 cm.

• Select a plant specimen bearing flowers/ fruits or both. A plant specimen without a flower or fruit is difficult to identify. Wrong identification may spoil all the results obtained in the study.

• While collecting the specimen for making herbarium specimen please also collect the 'associated information' like- the habit of the plant (herb/shrub/ tree/ climber etc), habitat of the plant (on rocks/ aquatic/ epiphyte/ grassy slope etc), place of collection, the elevation of the place, flower colour, specific aroma (if present), date of collection, name of the collector, local/ vernacular name, local use of plant, abundance in the nature etc.

• With the availability of good cameras in cell phones photography is almost always possible; so take a few photographs of plants growing in nature with good close-ups of flowers and fruits. Such photographs help a lot in the correct identification of plants.

• The collected plant should be spread on an old newspaper sheet in a way that leaves do not overlap and flowers/ fruits are visible. One or two leaves may be inverted to show under surface of the leaves. Cover the plant specimen with another sheet and press it under a weight of a few kg. After 12- 24 hours open the newspaper sheet and rearrange leaves etc to bring the specimen into proper shape. Replace the newspaper sheet with a new and dry sheet and press it again. The majority of specimens require frequent changes of newspaper sheet till the specimen becomes dry in 7- 10 days.  Used newspapers can be sun-dried and used again.

• 'Associated information' written by pencil on a white paper sheet should also be kept with the specimen.

• Bring the specimen in dried and loose form (not pasted on the herbarium sheet).

How to submit a voucher specimen!

• Bring specimen to Herbarium, Department of Biological Sciences, CBSH, Pantnagar

• Submit an application, duly forwarded by your advisor/ PI, addressed to the Head, Department of Biological Sciences, CBSH, for submission of voucher specimen. The format can be downloaded from here: 

• Application for submission of voucher specimen(s)- PDF 

• Submit other required details related to your place of research work, type of research (phytochemistry/ medicinal use/ molecular biology etc.), contact details etc. which are essentially required with the specimen. Format is available here which can be downloaded, printed and used.

•  DOWNLOAD FORMAT (MS Word), PDF 

• Once the voucher specimen is properly identified and submitted in the herbarium we can provide you the Herbarium Accession Number which can be mentioned in the manuscript of any research article. On a requirement, the link to the image of the voucher specimen will also be made available.

Please remember that you have to collect and dry the specimen only. Mounting will be done by us. 

Ask for help if you need it.