Phytolith analysis of sediments identify cultivated and encouraged plants at the Early Agricultural fields of Las Capas, Arizona

Phytolith analysis of field sediments at the Early Agricultural site of Las Capas documents a rich microfossil record of cultivated and encouraged plants that grew in farmed irragric soils. Maize is well-represented, but there is a strong indication of encouraged, if not cultivated, cool-season C₃ grasses, likely Hordeum sp. (little barley), suggesting these grasses were incorporated into the agricultural cycle, perhaps extending seasonal production of the field system. Other identified economically useful plants include sedges, common reed, composites (sunflower family), and bottle gourd. Species from the surrounding natural environment, ranging from the bajada to montane zones, include pine and hackberry. Additionally, the identification of freshwater sponge spicules and gemmoscleres demonstrates that water in the Santa Cruz River flowed consistently and cleanly for extended periods of time in the reach that irrigated Las Capas fields. The phytolith record complements and expands other "conventional" environmental studies such as pollen and macrobotanical analyses.