Geotaxia, geotactismo is the same as Geotropism or gravitropism. It refers to the effects presented the force of gravity with respect to the development of certain organs of the plants. They can be positive or negative. For example the roots have geotactismo or geotropism positive, as they are left to attract the gravity and that grow toward the center of the Earth; the branches or stem have negative geotactismo as they move away from the center of the Earth ( Geotactismo negative, but positive phototropism )
It is a reaction to a stimulus that is also called geotaxia, and in particular, is the response to gravity. There is also the phototaxis or in response to temperature and, finally, the quimitaxia or chemotaxis, which would be phototactism which is the reaction to light, the termotactismo or termotaxia, to a chemical.
