According to the US Forest Service paper, about 640 different species of trees in the US, 186 of which are endemic. Maps below present the entire tree species richness and endemic tree species in the US. These maps are based on data presented in Atlas of United States Trees. Maps of tree species richness of the United States The southeastern US has the greatest species diversity of trees. The most notable quantity of species of trees grows in the US states of Mississippi, Alabama, Georgia, and Florida. Liberty County in Florida has the highest tree species richness (138 species) in the US. Maps of tree endemic species richness of the U.S. The southeastern US also has the highest endemicity of tree species. The most significant number of endemic tree species also grow in Liberty County (Florida). Top 10 most common tree species in the U.S. Red Maple or ( Acer rubrum ) Loblolly Pine or ( Pinus taeda ) Loblolly Pine or ( Pinus taeda ) Douglas Fir or ( Pseudotsuga menziesi...