Hydrotropism(Bot) In a broader sense, any curvature or turning induced in certain growing plant organs under the influence of moisture.
Century Dictionary and Cyclopedia
nhydrotropismA state induced in a growing organ by the influence of moisture, in which under certain conditions it turns toward the moisture, and under other little understood conditions it turns away from the moisture. Organs which curve so as to apply themselves to the moist surfaces are termed positively hydrotropic; those which are induced to curve away from the dampness are termed negatively hydrotropic.
Chambers's Twentieth Century Dictionary
nHydrotropismhī-dro-trop′izm the habit induced in a growing organ by the influence of moisture, of turning toward, or away from, the moisture