XVI International Botanical Congess
This paper discusses a group of native plant species of the Southwest of North America which by virtue of their biology and their record of prehistoric, historic and present-day occurrence represent a weed flora that has evolved over thousands of years in relation to the development of prehistoric agriculture. The historic and present-day ethnobotanical record shows that most of these plants have beed extensively encourageor manipulated by aboriginal Southwestern agriculturalists. Populations of these species found in today's environment are thought to represent a living ethnohorticultural heritage of the prehistoric aboriginal peoples of the Southwest. Initial field observations and study of herbarium specimens show that many populations of these species have a higher than expected degree of morphological variation, which may reflect their selection by humans. Unlike the more invasive and competative non-native weeds, the native weeds have more mutualistic behaviors, such as that nearly all are entomophilous, which may reflect part of their role within the aboriginal agroecosystem.