The virtual herbarium allows on-line access to (label) data originating from collections kept at the NHN. For particular groups of collections (type specimens, the von Siebold collections at Leiden, microscopic slides of part of the wood samples at the Utrecht branch) digital images are available on-line as well. The three branches of the NHN (the herbaria of L, U and WAG) house an estimated 5.5 million collections. At present (2002) the website provides data extracted from about 350.000 collections. Data entry resulting in the present database was carried out by permanent staff (research and collection management), but mostly by project staff. Large parts of the data presented here have been accumulated in two projects funded by the Dutch Science Foundation (NWO), the Type Registration Project and its sequel, for which NWO is gratefully acknowledged. Prior to the onset of data entry a guideline was developed describing the data entry rules (field names, descriptions, range/values, format) following where possible international standards like those proposed by TDWG (http://www.tdwg.org/standrds.html). The guidelines for data entry currently in use are laid down in a Data Guidelines document.
Software used to build and maintain the database is BRAHMS (Botanical Research And Herbarium Management System) developed by the Department of Plant Sciences at Oxford. For more information about BRAHMS please visit http://herbaria.plants.ox.ac.uk/bol/home/.
Digital images were taken with a Leaf Lumina digital scan camera at a maximum resolution of 300 dpi. Files were saved in JPG-format and named after the barcode of the respective sheet. Because of the fixed camera and computer set-up (no need to re-focus after every herbarium sheet) no images were taken of most non-Phanerogam groups like Fungi, Musci and Algae. Image files were copied to CD. Prior to the Web presentation, using a macro, each image file was reduced to a thumbnail-size image (10-15 KB) and an image of 140DPI (40-250 KB) which still allowed the viewer to read label data. The link between the image file and the data lies with the barcode.
ETI Amsterdam (http://www.eti.uva.nl/) supplied the application to allow Internet access to the database. In fact the database available is a static copy of the live database and is being updated at regular intervals.
For more information: Luc Willemse.
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