Involved in the regulation of pedicel length and of CLAVATA pathways controlling stem cell identity at shoot and flower meristems. H2O + O-phospho-L-seryl-[protein] = L-seryl-[protein] + phosphate H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate Binds 2 magnesium or manganese ions per subunit. Insensitive to okadaic acid. Expressed in roots, leaves, stems, inflorescences, flowers and throughout the shoot meristem. Expressed throughout development of the floral meristem, in all four floral whorls and as floral organs matured, limited to the ovule. The N-terminal domain (1-233) has a regulatory function and inhibits phosphatase activity. The conserved PP2C phosphatase domain (271-833) is interrupted by an insertion of approximately 200 amino acids. Loss-of-function mutant pol-6 (T-DNA insertion) shows suppression of clavata mutant phenotypes. The catalytic activity of POL may be functionally replaced by the activity of PLL1. Pol and pll1 double mutant is seedling lethal. Belongs to the PP2C family.