Effect of the synthetic auxin 1-NAA on lateral inflorescence outgrowth from excised nodes of the wild type and axr1-12. The lowermost cauline node was excised from the elongating primary inflorescence of axenically grown plants and inserted between two separate agar slabs. Slabs contained either no 1-NAA or 1 or 10 μm 1-NAA in contact with the apical or with the basal part of the stem. Mean lateral shoot lengths ± se were determined each day until d 8 following excision. Measurements for some lateral shoots that wilted and ceased elongating after d 5 were included in the earlier time points but were excluded from the later time points. Node numbers tested for each treatment are: ○, 0 μm 1-NAA apical/0 μm 1-NAA basal, 5 to 8 wild type and 14 to 16 axr1-12; ▵, 0 μm 1-NAA apical/1 μm 1-NAA basal, 4 to 6 wild type and 5 axr1-12; □, 0 μm 1-NAA apical/10 μm 1-NAA basal, 4 wild type and 5 to 6 axr1-12; ▴, 1 μm 1-NAA apical/0 μm 1-NAA basal, 12 to 15 wild type and 10 axr1-12; ▪, 10 μm 1-NAA apical/0 μm 1-NAA basal, 8 wild type and 12 to 13 axr1-12.