Eleven plants were chosen so as to cover a wide range of biological characteristics (perennial, annual, autogamous, allogamous, etc.) in this study. Three chapters on methodology complement these studies. The first is devoted to the use of biological and molecular markers to analyse the diversity of collections, the second addresses data analysis, and the third describes a method for constituting core collectaions based on maximization of variability.

Biochemical and molecular markers: Laurent Grivet and Jean-Louis Noyer; Methods of data analysis: Xavier Perrier, et al.; A method for building core collections: Michel Noirot, et al.; Asian rice: Jean-Christophe Glaszmann, et al.; Banana: Christophe Jenny, et al.; Cacao: Claire Lanaud, et al.; Cassava: G�rad Second, et al.; Citrus: Patrick Ollitrault, et al.; Coconut: Patricia Lebrun, et al.; Coffee (Coffea cnephora): St�phane Dussert, et al.; Pearl Millet: Gilles Bezancon; Rubber tree (Hevea brasiliensis): Marc Seguin, et al.; Sorghum: Monique Deu, et al.; Sugarcane: Jean-Christophe Glaszmann, et al.