The Burseraceae are characterized by the nonallergenic resin they produce in virtually all plant tissue and the distinctive smooth, yet flaking, aromatic bark. The origins of the family can be traced to the Paleocene (about 65 Mya) when "Beiselia mexicana" first diverged in Mexico. The subsequent divergences in the family lineage and migration of the species in the Eocene (53 Mya) from North America have led to the current distributions of the species that are primarily associated with the tropics. Though the family likely originated in North America, the greatest genetic diversity presently is in the Southern Hemisphere. Tabonuco ("Dacryodes excelsa") and gumbo limbo ("Bursera simaruba") represent the economic, ethnobotanical, and ecological significance of the Burseraceae in the Western Hemisphere, while frankincense ("Boswellia sacra") and myrrh ("Commiphora myrrha") represent the same in the Eastern Hemisphere.