Reversible blockage of the cell cycle in the meristem of Riella helicophylla (Bory et Mont.) Mont. by p-chlorophenoxyisobutyric acid (PCIB).

Treatment of gemmae of Riella helicophylla with PCIB results in reversible blockage of the meristematic cells in the G1-phase. At the same time the normal subdivision of the intercalary meristem into two lateral meristems disappears. PCIB is effective only when the plants are exposed to light.