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A diurnal movement of plant parts, such as the opening during the day and closing during the night of certain flowers.
[Greek nux, nukt-, night; see nekw-t- in the Appendix of Indo-European roots + -nasty.]
nyc′ti·nas′tic (-tĭk) adj.
(Botany) botany a nastic movement, such as the closing of petals, that occurs in response to the alternation of day and night
[C20: from Greek nukt-, nux night + -nasty]