NON-REVERSION OF IMPATIENS IN THE ABSENCE OF MERISTEM COMMITMENT

purple-flowered plants of impatiens balsamina maintained floral develo pment on transfer from inductive short days (SD) to long days (LD), a treatment in which red-flowered plants of Impatiens are known to rever t to leaf production. An investigation into the nonreverting nature of purple-flowered plants was carried out to establish whether these pla nts 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 purple-flowered plants did revert. This result suggests that, as in red-flowered Impatiens, meristem commitment is absent, but that pu rple-flowered plants maintain flowering in LD conditions because of a more permanent supply of signal from their leaves than occurs in red-f lowered plants. A working hypothesis is proposed to explain how a sign al from the leaves can retain a controlling role during flower develop ment.