Throughout history, wild green vegetables have played a significant role in human diets around the world, coevolving alongside agriculture and changing land use patterns (Wilson, 1990). Wild greens such as purslane (Portulaca oleracea), lambquarters (Chenopodium spp.) and amaranth (Amaranthus spp.), wild ancestors of crop plants, are prehistoric foods that are cultural and nutritional mainstays in many parts of the world including the Arizona-Mexico borderland region. While consumption of these foods is commonplace on the Mexican side of the border, on the American side their use is less frequent. In this study, I explore the patterns of and barriers to consumption of wild green vegetables by Latinos living in the Arizona (AZ)-Mexico (MX) borderland city of Tucson, AZ. I use Weber's rationalization theory, as well as human agency theory, to guide my exploration of how the dominant food system contributes to dietary acculturation and the loss of agency among Latinos living in Tucson. In-depth interviews and naturalistic observations are employed across a diverse array of market settings, which include a farmers' market, several carniceri­as (Mexican butcher shops), a corner store/tortilleria with procurers and purveyors of Latino and indigenous foods, and a more conventional supermarket. The findings reveal a reduction in knowledge and consumption of heritage greens by Latinos concurrent to their adoption of more mainstream American foods. I consider this pattern and its various implications in the context of the rationalization of the dominant U.S. food system, which leads to a dynamic that favors efficiency and productivity over authenticity and aesthetics.