-nyctitropic-

a. [ From Gr. ny`x, nykto`s, night + &unr_; turning. ] (Bot.) Turning or bending at night into special positions. [ 1913 Webster ]

☞ Nyctitropic movements of plants usually consist in a folding or drooping of the leaves, the advantage being in lessening the radiation of heat. [ 1913 Webster ]