We surveyed foliar morphological and chemical variation in 31 clones of Populus tremuloides in northern lower Michigan. Significant variation among clones was exhibited for leaf weight, specific leaf area, nitrogen, starch, phenolic glycosides (salicortin and tremulacin) and condensed tannins. Variation among clones with respect to nitrogen, starch, salicortin, tremulacin and condensed tanning concentrations was 1.7-, 8.0-, 10.3-, 5.9-, and 2.1-fold, respectively. Interactions between aspen and phytophagous insects in this region are likely to be ifluenced by substantial interclonal variation in secondary chemistry.