tropism

emma cunningham ~ 1/31/14 ~ 3rd period

tropism

the turning of all or part of an organism in a particular direction in response to an external stimulus.

geotropism

the growth of the parts of plants with respect to the force of gravity. The upward growth of plant shoots is an instance of negative geotropism ; the downward growth of roots is positive geotropism.

hydrotopsim

the growth or turning of plant roots toward or away from moisture.

phototropism

the orientation of a plant or other organism in response to light, either toward the source of light ( positive phototropism ) or away from it ( negative phototropism ).

thigmotropism

the turning or bending of a plant or other organism in response to a touch stimulus.