P uptake kinetic parameters. Average (± SE) phosphorus (P) uptake kinetic parameters for Cladium mariscus spp. jamaicense and Typha domingensis acclimated to low (5 μg l-1) and high (500 μg l-1) P concentrations and high (+O2: 8 mg l-1) and low (-O2: <0.5 mg l-1) oxygen concentration in the culture solutions. Uptake was measured by P depletions of root solutions followed by stepwise increments of the P concentrations. The kinetic parameters: (A) Vmax (maximum uptake at saturating P concentration), (B) K0.5 (half saturation constant), and (C) Cmin (P concentration where there is no net uptake) were estimated by fitting to a modified Michaelis-Menten model.