long-day photoperiodism photoperiodism, flowering long-day photoperiodism, flowering short-night photoperiodism, flowering long-day photoperiodic control of flowering long-day photoperiodic control of inflorescence development GO:0048574 biological_process long-day photoperiodic control of flowering time A change from the vegetative to the reproductive phase as a result of detection of, or exposure to, a period of light that exceeds the critical day length. The critical day length varies between species. Although the term is long-day is used, most species actually respond to the duration of the night, so that the response will occur when a period of darkness falls short of the number of hours defined by 24 minus the critical day length. response to short-night, flowering response to long-day, flowering