Two greenhouse experiments were conducted to compare the growth of individual sulfonylurea-resistant and -susceptible kochia under noncompetitive conditions. Aboveground leaf and stem dry weight, and leaf area per plant were measured weekly 14 times, starting 14 d after planting. Data were fitted using the Richards function for shoot dry weight per plant, a polynomial exponential for leaf area per plant and splined function to calculate leaf area ratio, leaf weight ratio, and leaf/stem ratio. Absolute and relative growth rates, and net assimilation rate were derived from these functions. Growth and development of individual sulfonylurea-resistant and -susceptible kochia plants under noncompetitive conditions was the same. Final shoot dry weight and leaf area were unaffected by aceto lactate synthase enzyme differences in the kochia biotypes. However, more resources were partitioned to leaves than stems in resistant than in susceptible kochia. If competitive abilities of sulfonylurea-resistant and -susceptible kochia are different, it is not the consequence of differential growth and ontogeny of the two types of plants.