A full description is presented of the Juglandaceae and of the 2 subfamilies (Platycaryoideae and Juglandoideae), 3 tribes of the Juglandoideae (Juglandeae, Engelhardieae and Hicorieae) and 7 genera [Platycarya, Juglans, Pterocarya, Engelhardia, Oreomunnea, Alfaroa and Carya] with their subgenera and sections. Figures and tables are given to illustrate the evolution of the genera, the comparative classifications within the family and the comparative interpretations of the parts of the floral envelopes. Diagrams are presented of the position of the carpels, the orientation and type of the stigmas, and the parts of the floral envelopes. A list is given of the 59 spp. with the subspecies and varieties, including their distribution.