It is a distressing truism that the human race during the last millennium has caused the exponential loss of plant genetic diversity throughout the world. This has had direct and negative economic, political and social consequences for the human race, which at the same time has failed to exploit fully the positive benefits that might result from conserving and exploiting the world's plant genetic resources. However, a strong movement to halt this loss of plant diversity and enhance its utilisation for the benefit of all humanity has been underway since the 1960's (Frankel and Bennett, 1970; Frankel and Hawkes, 1975). This initiative was taken up by the Convention on Biological Diversity (CBD, 1992) that not only expounds the need to conserve biological diversity but links conservation to exploitation and development for the benefit of all. Article 8 of the Convention clearly states the need to develop more effective and efficient guidelines to conserve biological diversity, while Article 9, along with the FAO International Undertaking on Plant Genetic Resources, promotes the adoption of a complementary approach to conservation that incorporates both ex situ and in situ techniques.

1 The Genetic Resources of Plants and Their Value.- 1.1 The Biodiversity Challenge.- 1.2 The Definition of Biodiversity.- 1.3 Plant Genetic Resources.- 1.4 The Need to Conserve Botanical Diversity.- 1.5 The Causes of Plant Genetic Diversity Loss.- 1.6 The Conservation / Development Paradox.- 1.7 The Exploitation of Plant Diversity in Crops.- 1.8 The Practice of Conservation.- 1.9 The Advantages and Disadvantages of Different Ex Situ Techniques.- 1.10 Complementary Conservation Strategies.- 2 Evolution of Plants Under Domestication.- 2.1 Plants: Cultivated and Wild.- 2.2 Genetic Changes During Domestication.- 2.3 Alphonse de Candolle's Views on Cultivated Plant Origins.- 2.4 Darwin's Views on Plant Domestication.- 2.5 The Ecological Background of Plant Domestication.- 2.6 N.I. Vavilov's Centres of Crop Origins and Diversity.- 3 The Plant Genetic Resources Conservation Movement.- 3.1 Ethical and Conservation.- 3.2 A Brief History of Plant Genetic Conservation and Use.- 3.3 Critical Issues for Contemporary Plant Genetic Resources.- 4 Preparing To Collect For Ex Situ Conservation.- 4.1 Conservation Project Commission.- 4.2 Selection of Target Areas.- 4.3 Selection of Target Species.- 4.4 Ecogeographic Surveys.- 4.5 Selection of the Collection Team.- 4.6 Expedition Timing.- 4.7 Local Administrative Requirements.- 4.8 Collecting Equipment.- 4.9 Survey Missions.- 5 Exploration and Field Collection.- 5.1 Sampling Techniques.- 5.2 Types of Collecting Site.- 5.3 Field Sampling.- 5.4 Specialised Type of Plant Collecting.- 5.5 Conservation Products.- 5.6 Duplication of Collected Materials.- 6 Seed Gene Bank Conservation.- 6.1 Conventional Ex Situ Techniques.- 6.2 Base and Active Gene Banks.- 6.3 Seed Storage.- 6.4 Intermediate and Recalcitrant Seeded Species.- 6.5 Users ofSeed Stored in Gene Banks.- 7 Field Gene Banks, Botanic Gardens In Vitro, DNA and Pollen Conservation.- 7.1 Field Gene Banks and Orchards.- 7.2 Botanic Gardens.- 7.3 In Vitro Techniques.- 7.4 DNA Storage.- 7.5 Pollen Storage.- 8 World Ex Situ Collections of Germplasm.- 8.1 World Collections of Major Crops.- 8.2 Numbers of Accessions in Storage.- 8.3 Security of Collections.- 8.4 The Cost of Conservation.- 8.5 How Unique Are Accessions Within Gene Banks?.- 8.6 Field Gene Banks, In Vitro Storage and Botanic Gardens Collections.- 8.7 How Much is Enough?.- 8.8 Core Collections.- 9 Community-Based Conservation.- 9.1 Local Communities And Conservation.- 9.2 Communities Working To Conserve Plants.- 9.3 Communities Working With Professional Conservationists.- 9.4 Communities and Professional Conservationists Working Together.- 10 Plant Genetic Resource Utilization.- 10.1 Germplasm Exploitation.- 10.2 Phenotypic Characterisation and Evaluation.- 10.3 Genetic Evaluation and Analysis.- 10.4 Use of Molecular Markers in Germplasm Evaluation.- 10.5 Evaluating the Value of Conserved Plant Diversity.- 10.6 Direct Utilisation of Genetic Resources.- 11 Genetic Conservation Information Management.- 11.1 The Need For Information Management.- 11.2 Data Capture and Manipulation.- 11.3 Accessing Existing Conservation Information.- 11.4 The Efficient Management of Conservation Data.- 11.5 Central Crop Databases.- 11.6 Data Ownership.- 12 Conservation Case Studies.- 12.1 Case Studies of Plant Genetic Resource Conservation.- 12.2 Rice.- 12.3 Wheat.- 12.4 Potatoes.- 12.5 Bananas and Plantains.- 12.6 Coffee.- 12.7 Clover.- 12.8 Leucaena.- 12.9 Asiatic Slipper Orchids.- 13 The Future of Ex Situ Conservation.- 13.1 Towards the Future.- 13.2 The Human Population and its Impact.- 13.3 Specific Ex Situ Conservation Activities.- 13.4 Human Needs Linked to Biodiversity Conservation.- 13.5 Conservation Actions for the New Millennium.- References.- Appendices.