The leaves of 23 spp. of deciduous trees were analyzed at 3 intervals during the growing season. The dry matter of young leaves contained the largest percentages of P, K, and N, whereas the mature leaves collected at the end of the growing season contained the largest percentages of ash, silica, and Ca. Cu, Mn, and Zn were normal constituents in all of the samples. In sweet gum, black oak, and pin oak, the Mn content was in excess of the Fe content, which is an unusual relationship. The leaves of these trees develop beautiful colors during the late autumn season, and the unusual relationship of Fe and Mn may be a factor in the production of these autumnal shades. The results do not afford material evidence that mineral nutrients migrate from the leaves to the branches toward the end of the growing season. A mixed forest probably would add as much plant nutrient to the surface soil in an annual crop of leaves as is removed by the average forest crop.