Starch Granule Evidence for Biscuitroot (Lomatium spp.) Processing at Upland Rock Art Sites in Warner Valley, Oregon

Geophytes are hardy, resilient plants that are tolerant of cold temperatures and drought and are well documented as a reliable food source for hunter-gatherers worldwide. Human settlement patterns and foraging behaviors have long been associated with the use of nutrient-dense geophytes rich in carbohydrates, fiber, vitamins, and minerals. Indigenous communities in the northern Great Basin developed cultural practices centered around gathering, preparing, and consuming important geophytic plants. These practices became deeply embedded in their cultural identity, forming rituals, stories, and traditions that persist today. Although there is strong ethnographic precedent for the significance of geophytes, finding evidence of their use in the archaeological record remains a challenge. This study analyzed archaeological starch residue extracted from bedrock metates in the uplands of Warner Valley, Oregon. Systematic studies of starch granules collected from extant plant communities growing near archaeological sites were applied to the identification of archaeological granules. Starch granules from geophytes, specifically Lomatium spp. (biscuitroot), were identified on metate surfaces at all sites, thus providing direct evidence for the collection and processing of geophyte vegetables. Evidence of geophyte plant processing on bedrock metates contributes to archaeological theories about subsistence strategies, food-processing technologies, social organization, and cultural practices in past human societies.