In recent decades, the development of archaeobotany in the western Mediterranean has made it possible to document the main plant resources exploited, the agricultural practices implemented, as well as major phenomena of circulation and integration of new plant resources within historical societies. During the Middle Ages, Iberia is for a great part under Muslim rule, and is the theater of what has been widely considered in the literature as a “green revolution”. This period also sees the expansion of the northern Christian kingdoms into the Peninsula, often found under the debated name of “Reconquista”, that ended in 1492 with the fall of Granada. These changes disrupted economic systems, demographic and environmental pressures which changed radically, entering a new scale. But what effect did they have on agriculture? Regarding the reel expansion of medieval Arab-Berber agriculture in Iberia and the so-called “green revolution”, we hypothesize that it was in fact limited to A) the landed estates that depended on the urban aristocracy, and B) to the large areas of specialized production well known from the written sources. But how was agriculture practiced in the rural areas far from these productive regions: did they evolve as in Andalusia? Perpetuate ancient practices (Iberian, Roman)? Or undergo developments similar to those observed in neighboring Christian regions (Mediterranean France)? Regarding the areas that come under Christian rule, the weight of the Andalusian agricultural legacy is yet to be determined, although we hypothesize continuity in the staple productions and practices. To document these questions, the main objectives of this paper are: 1) to reconstruct ancient agrosystems and agrobiodiversities using archaeobotanical data; 2) to assess how societies, depending on local environmental parameters, have developed their agrarian strategies, following the evolution of the cultural and socio-economic context; 3) to determine what role socio-economic dynamics have played in the large-scale diffusion of certain agricultural productions. The paper will present results of new studies carried out in a range of frontier medieval sites in Spain (Aragon, Catalonia, Extremadura, Guadalajara, Malaga, Ibiza), a large part of which is drawn from the research project "Landscapes of (Re)Conquest: Dynamics of Multicultural Frontiers in Medieval South Western Europe", funded by AHRC. The results, based on studies of seeds remains issued from samples dated from the 10th to the 15th c., make it possible to draw up a list of the main agro-horticultural productions and their evolution in the face of changing socio-economic dynamics.