Archaeobotany remains an underdeveloped discipline in the Arctic, with comparatively little known about the processes involved in the formation of plant assemblages in ancestral Inuit sites. Archaeobotanical records from seasonal forager sites at high latitudes present several peculiarities: 1) excellent preservation; 2) lack of domesticated species prior to contact with Europeans; 3) few, if any, carbonized remains; 4) taxa from the immediate environment. Under these conditions, it can be difficult to differentiate between macrobotanicals resulting from human activities and those introduced naturally during or after site occupation. In this article, we present the results of archaeobotanical analysis of an early Thule Iñupiaq winter dwelling dated to the late 13th – early 14th centuries at Cape Espenberg (KTZ-304), northwestern Alaska. In order to define plant-related practices among past Iñupiat people, we are attempting to determine how the archaeobotanical assemblage is formed, and delineate the macrobotanical remains associated with human activities. Comparison of roof and cultural layer samples with fill and off-site samples, as well as the results of five 14C dates on seeds, provide a clear archaeobotanical signature of the cultural levels and demonstrate that the plant assemblage associated with the occupation layers derives from human activities directly and indirectly linked to plant use.