Full domestic agriculture in the North American continent has its roots in Mexico. Corn or maize (Zea mays) and beans (Phaseolus vulgaris) were both domesticated there, corn perhaps as long ago as 10,000 years. Eventually, these crops turned up in North American garden plots, depending on which date you believe in which location you are talking about, but somewhere around 3000 years before the present.
The Eastern Agricultural Complex refers to the whole range of plants that were selectively tended by Native Americans in eastern North American and the American midwest before corn and beans reached there, like sumpweed (Iva annua), goosefoot (Chenopodium berlandieri), sunflower (Helianthus annuus), little barley (Hordeum pusillum), erect knotweed (Polygonum erectum) and maygrass (Phalaris caroliniana).
Evidence for the collection of some of these plants goes back to about 6000-5000 years ago; their genetic modification resulting from selective collecting first appears about 4000 years ago.
Sources and Further Information
See links for specific crops on the Guide to Plant Domestication.This glossary entry is part of the About.com Guide to Ancient Farming and the Dictionary of Archaeology.
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