Schematic drawing of the field experiment set up and light treatments. Dark: plants exposed on dark control sites; illuminated: plants exposed on illuminated sites; adjacent: plants exposed to a dark site but adjacent to the illuminated site. Light intensity in dark and adjacent treatment is comparable, see text for details. Mean distance (in meters) ± s.e.m. of the phytometers from the lamp (illuminated and adjacent sites) and fake lamp (dark sites) are shown.