The emerald ash borer (Agrilus planipennis, EAB), a beetle native to East Asia, has decimated populations of trees in the Fraxinus (ash) genus since its unintentional introduction into Southeastern Michigan, USA in the late 1990s. The larval stage of the EAB lifecycle devastates ash populations through the consumption of phloem tissue beneath the bark, impacting system-wide carbohydrate transport. In addition to the increased mortality of ash trees themselves, EAB-induced death can have significant influence on the surrounding ecosystem. This is a particular concern for Fraxinus nigra (black ash) due to the unique habitat and ecosystem services it provides, including the swamps, bogs, and other moisture-rich wetland landscapes it dominates. The potential large-scale death of black ash from EAB infestation threatens the foundational ecosystem function of these hydric systems, as black ash is one of very few deciduous trees present in these wetland environments. As such, it is imperative to evaluate within and among population variability, at both phenotypic and genomic levels, to uncover drivers of EAB resistance that can be leveraged to conserve this keystone species. In this work, seed and samara morphology will be evaluated in black ash trees across its North American range to identify shifts in seed-related phenotypes that may contribute to differential, reproductive-based responses to EAB within and among populations. Responses will be assessed through the measurement of samara and seed traits derived from x-ray images, as well as seed weight. These findings will offer insight into putative population-specific mechanisms linked with seed dispersal and/or seedling establishment in the face of EAB infestation. We hypothesize that: 1) populations closer to the outbreak origin will exhibit lower seed weights and smaller samaras, suggestive of a generalized stress response to EAB that impacts reproductive success; this will also correspond with an increase in the amount of unfilled seeds per mother tree, and 2) populations further from the epicenter will display higher seed weights, larger samaras, and fewer unfilled seeds, facilitating population expansion with competitive seedlings.