Non-reversion of Impatiens in the absence of meristem commitment

Purple-flowered plants of Impatiens balsamina maintained floral development on transfer from inductive short days (SD) to long days (LD), a treatment in which red-flowered plants of Impatiens are known to revert to leaf production. An investigation into the nonreverting nature of purple-flowered plants was carried out to establish whether these plants achieved meristem commitment or whether their non-reverting state was controlled by the leaves. When the leaves that had unfolded during the inductive SD treatment were removed at the time of transfer to LD, the purpleflowered plants did revert. This result suggests that, as in red-flowered Impatiens, meristem commitment is absent, but that purple-flowered plants maintain flowering in LD conditions because of a more permanent supply of signal from their leaves than occurs in red-flowered plants. A working hypothesis is proposed to explain how a signal from the leaves can retain a controlling role during flower development.