Plant data are managed at UNEP-WCMC using BG-BASE, a variable-length field, relational database management system built using Advanced Revelation, and widely adopted by botanical institutions throughout the world. The database is externally dynamic with over 100 changes and additions made per day; all records are date-stamped and initialled so that changes to records can be easily tracked. Full-word, partial- word, and phonetic searches are available to streamline data entry and retrieval.

Managing plant data on a global scale is a complex task, especially given the range of diverse uses that the database serves at UNEP-WCMC, for instance, production of the plant data are found in the Checklist of CITES Species (WCMC, 1996) and World Plant Bibliography (Anon, 1990). Therefore, the database management system used is large and incorporates many more features than would be necessary simply to produce this list. For maximum efficiency, BG-BASE data are managed in a series of database tables (or files) whose constituent records are related to one another through shared fields. BG-BASE has over 4,200 fields spread across approximately 200 database files, of which UNEP-WCMC uses a relatively small percentage. The major BG-BASE tables used by UNEP-WCMC are shown below.

When plant information is received by UNEP-WCMC, the first step taken is to create a data source record in the DS table (19,076 records) for that information. These data source records are mostly books, journal articles, proceedings, and other published work, but they can also be conversations, and annotations made to UNEP-WCMC lists, etc. The location of each data source is coded so that it may be found quickly; full citation details can be output as camera-ready bibliographies. The key field in this table is DS. NUM, the number shown throughout this book and in the DATA SOURCES section following the main list.

The Threatened Plants database already contains information on nearly half of all known vascular plants. When "new" taxa are added, a record is created in the NAMES table, which handles information on the scientific name, common names, and languages and synonymy. Accepted names and synonyms are linked and indexed together so that any name searched for, automatically brings up all relevant records.

If the nomenclatural and taxonomic status of a name has not been verified, the name is coded as "unchecked" (note such names have not been suppressed from this List). Information about the taxon's habit (tree, shrub, herbaceous, etc.) and uses (timber, wild crop relative, etc.) is also collected where possible. Selections of data from the NAMES table are periodically downloaded to BGCI allowing conservation audits of botanic gardens worldwide to be undertaken, an example of which is given in the Utrecht University catalogue of plant collections (Wollenberg et al, 1992). Further tables allow inventory data for protected areas to be stored (Murray et al, 1992).

Each NAMES record is linked to a record in the GENERA table, where records are in turn linked to the FAMILIES table. CITES information is stored in all three of these tables, as appropriate, depending on what taxonomic level is listed.

For each area of the world in which a plant is said to occur, a separate record is created in the DISTRIBUTIONS table. These records, besides holding pointers to the name of the plant and the name of the area (stored in the BRUs table), contain information on the geographic area to which the plant may be restricted, the data source for the distribution information, the conservation status (IUCN category and the status as given if the data source is not using IUCN categories), and the data source for this conservation information. Other fields which exist but which are relatively infrequently used by UNEP-WCMC include: number of individuals and/or populations of the taxon known to exist in the area, date(s) when the taxon was last seen in the area, threat(s) to the taxon in the area, legal status of the taxon in the area, presence in conservation areas, and habitats occupied by this taxon. Other fields used include Occurrence and Introduced flags, as specified in the POSS (Plant Occurrence Status Scheme) adopted by TDWG (Threatened Plants Unit, in press). All introduced records have been suppressed from this list.

Table 1 Major tables used in the UNEP-WCMC Threatened Plants Database

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Table	No. records	Table contents
NAMES	139,719	Information on scientific names of species and infraspecies (broken into 30 fields in order to be compatible with standards for storing scientific names of both naturally occurring and cultivated plants, see Walter, (1995), data source(s) for name, status of the name (accepted, invalid, orthographic variant, synonym, pro parte synonym, sensu synonym, not found in literature, tentatively accepted name, unchecked names), synonymy (multiple alternate names/synonyms can be linked to an accepted name), data source for the synonymy, vernacular names (as many as necessary, including language and data source), global IUCN conservation status, TNC global rank, presence on CITES Appendices (if listed at the species or infraspecies level), habit (tree, shrub, vine/liana, herbaceous, succulent) etc., use, and a flag for complete/incomplete distribution. By links to the GENERA table, full upper-level taxonomic information is available to each NAMES record. There are index links from the DISTRIBUTIONS table that allow instant queries of all distributions of a taxon.
DISTRIBUTIONS	191,100	Information on distribution (at BRU level 3 or 4, see Table 3), free-text area qualifier specifying area(s) in the BRU to which the taxon is restricted, introduced flag, occurrence flag, data source for distribution information, flag for existence of a distribution map in that data source, local threat status, data source for threat status, status as given (for storing non-IUCN threat status categories), numbers of individuals and/or populations known of this taxon in this BRU, date taxon was last seen in this BRU, threats to the taxon in this BRU, legal status of this taxon in this BRU, protected areas within this BRU in which the taxon occurs (linked to the UNEP-WCMC Protected Areas database of 40,000 records), habitat types occupied by this taxon in this BRU, and general data sources concerning this taxon in this BRU.
DATA SOURCES	19,076	Information on the published and unpublished sources of information for data in all other tables; fields include type of data source (book, journal article, chapter in book, unpublished, etc.), author(s), publication date(s), title, subtitle, journal name, volume, number, pages, publisher, place of publication, citation notes, location of reference, language of reference and of abstract, relevance codes, countries mentioned, families mentioned, genera mentioned, species mentioned, abstract, accuracy of citation, and access type. Bibliographies published from this include Anon. (1990) and Atkinson et al (1995).
GENERA	27,101	Information on all genera of vascular plants and many non-vascular plants; fields include genus, author, family placement (link to FAMILIES table), synonymy, status of the name (as under NAMES above), presence on CITES Appendices (if listed at the generic level).
FAMILIES	956	Family statistics (number of genera, number of species, number of threatened species), as well as global range are also stored here. Information on all vascular plant families and many non-vascular families; fields include family, preferred name (for family pairs such as Asteraceae/Compositae), major taxon, synonymy, vernacular name, number of species, number of genera, distribution, and phylogenetic placement according to various systems of classification.
COUNTRIES	243	Information on all countries of the world, including international abbreviation (see ISO, 1993). English name, official name, synonyms, land area, size of flora (numbers of pteridophytes, gymnosperms, angiosperms, and vascular plants, along with corresponding data sources), number and percent of endemic plant species along with corresponding data sources. Although BG-BASE does not code distributions at the country level, country-level queries can be done through calculations automatically performed by the BRUS table.
BRUS	1076	Information on all Biological Recording Units (see Table 3) including fields for level (1-4), level 1-4 codes and names (for tracking hierarchical nesting), BRU name, political name, English name, French name, German name, Spanish name, keyword (for spelling variants), land area, latitude/longitude, sorting order (for sorting the distributions under a taxon in this List). There are index links from the DISTRIBUTIONS table that allow instant queries for all taxa within a BRU.

As discussed under "Data Coverage and Quality" above, this list represents only a selection of the fields and records available within UNEP-WCMC's Threatened Plants database. Fields such as common name, habit and synonyms were suppressed for reasons of space. The kinds of database records that were excluded from this list are shown in Table 2