Columbia subject headings:
Harvard subject headings:
Monocotyledons--Classification.
Monocotyledons--Evolution.
Monocotyledons--Morphology.
Plant morphology.
Plants--Classification
Plants--Evolution
Princeton subject headings:
Monocotyledons--Classification.
Monocotyledons--Evolution.
Monocotyledons--Morphology.
Plant morphology.
Plants--Classification.
Plants--Evolution.