Forest trees cover one third of the global land surface, constitute many ecosystems and play a pivotal role in the world economy. Despite their importance in the economy, ecology and environment, genetic analysis and breeding efforts have lagged behind. Presented here are chapters on Populus trees, pines, Fagaceae trees, eucalypts, spruces, Douglas fir and black walnut, and a first-ever detailed review of Cryptomeria japonica. Innovative strategies to address the inherent problems of genome analysis of tree species are thoroughly discussed.