Two major floral stem extension rate oscillations were present in Arabidopsis: one with maxima during the light period and a second one with maxima during the dark period. These oscillations are, in some sense, probably independent because under homogeneous population (same clone, synchronised for flowering time initiation) and standard environmental measurement conditions the physiological FSER could be clearly separated into two distinct classes. In 79.2 %, the dark FSER oscillation had lower maxima than light oscillations. The remaining 20.8 % showed, after the middle of the whole stem growth period, greater maxima during the dark than during the light span. It also appeared that the rosette was approximately 1.5 times bigger in the second group. This suggests that, in a homogeneous clone population under the same environmental conditions, the amplitudes of the FSER rhythms may be modulated according to the importance of the vegetative part of the plant. Furthermore, we tried to develop a mathematical model fitting floral stem elongation data. It shows the possibility of the intervention of two different, independently modulated, rhythms.