Fig. 1.

Petiole elongation in 27-d-old Rumex palustris plants that were exposed to control growth conditions (Cox et al., 2003), submerged or spectrally shaded [white light filtered through one layer of Fern Green filter (Lee Filters no. 122, Andover, UK), PAR = 70 µmol m⁻² s⁻¹, R : FR (655–665 nm : 725–735 nm) = 0·2]. Plants were treated for 24 h and petiole elongation was measured as the increase in length between the start and end of the experiment of the third emerged petiole. Data are means (n = 3) ± s.e.