Definition of nyctinastic in English:

nyctinastic

adjective

Botany
  • (of the periodic movement of flowers or leaves) caused by nightly changes in light intensity or temperature.

    • ‘Several systems of measurement have been used to characterize leaf or leaflet orientation during nyctinastic and heliotropic movement.’
    • ‘Leaf-movement in nyctinastic plants has long been believed to be controlled by plant hormones that are common among all nyctinastic plants.’
    • ‘Leaflets of nyctinastic plants assume a vertical (i.e. closed) position in darkness and revert to horizontal orientation upon illumination.’

Origin

Early 20th century: from Greek nux, nukt- night + nastos pressed + -ic.

Pronunciation:

nyctinastic

/ˌnɪktɪˈnastɪk/