The conservation value of germplasm stored at the Millennium Seed Bank, Royal Botanic Gardens, Kew, UK

The Millennium Seed Bank (MSB) Partnership, developed and managed by the Royal Botanic Gardens, Kew (RBG Kew), conserves propagules primarily from orthodox seed-bearing wild vascular plants. It is the largest ex situ conservation programme in the world, currently involving 96 countries and territories. Where possible, seeds are collected and conserved in the country of origin with duplicates being sent to RBG Kew's MSB for storage. In this paper we assess the conservation value of the germplasm stored at the MSB using both quantitative and qualitative methods. The MSB holdings represent a high quality, rich biological resource. Substantial and unique taxonomic diversity exists amongst the collections, representing 365 families, 5813 genera, 36,975 species and 39,669 taxa conserved. The collections cover a wide geographic range, originating from 189 countries and territories, representing all nine bio-geographic regions and all 35 biodiversity hotspots. The collections possess significant natural capital and population value: 32% of taxa, representing 49% of collections, have at least one identified use to humans; and 74% of taxa, representing 78% of collections, are either endemic, endangered (nationally or globally) and/or have an economic, ecological, social, cultural or scientific value. While 10% of taxa, representing > 8% of collections, are either extinct, rare or vulnerable to extinction at the global and/or national level, 20% of taxa, representing 13% collections, are endemic at the country or territory scale. Over the 17-year period since 2000 at least 11,182 seed samples, representing 12% of taxa and 8% of collections, have been distributed globally for conservation, research, education and display. This analysis highlighted collection gaps in MSB holdings in relation to their geographic representativeness, the taxonomic diversity of large families and genera of angiosperms, and coverage of threatened taxa. Further analysis across the entire MSB Partnership is required to underpin future collection activities and maximize the usefulness of collections.