It is a rhizome which is a type of modified, underground stem. It bears nodes, internodes, and adventitious roots. Its strong aroma and taste are due to ketones called gingerols used as a spice, flavoring, food, and medicine.
Ginger has fine long tapering leaves with pointed tips and is very important in photosynthesis. They are edible and bear a gingery flavor that is not as strong as the rhizome.