designating, of, or exhibiting movement or change in position of a plant or its parts, as in the opening and closing of flowers, in response to a stimulus but independent of the direction of the stimulus and caused by unequal growth of certain cells, changes in light intensity, etc.
< Gr nastos, pressed close < nassein, to press, squeeze close + -ic
nastic by some (specified) means or in some (specified) direction: epinastic, hyponastic
See nastic in American Heritage Dictionary 4
Of, relating to, or characterized by the tendency in plant parts to move in a direction determined by an internal stimulus, as an increased rate of cellular growth on one surface or side of the plant part.
Origin: Greek nastos, pressed close (from nassein, to press)