Columbia subject headings:
Harvard subject headings:
Agriculture--United States--History
Ethnobotany--United States.
Natural history--United States
Phytogeography--United States.
Plant ecology--United States
Princeton subject headings:
Agriculture--United States--History.
Botany--United States--Ecology.
Ethnobotany--United States.
Natural history--United States.
Phytogeography--United States.