When roots and shoots grow in opposite directions, they reflect contrary responses to Earth’s gravitational field. Geotropism (Greek: ge, “earth”), or gravitropism, are the names given to this physiological process. Most roots are positively geotropic; that is, they grow in the direction of gravity. Stems, for the most part, are negatively geotropic, growing opposite to the gravitational force. When rhizomes, stolons, and some roots grow horizontally, they display diageotropism (Greek: dia, “across”). And branches from roots and stems, developing at an angle from the vertical plant axis, are
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