The use of herbicides is increasing because they are essential to ensure food safety, especially in the increasing need for food production. However, their misapplication leads to significant environmental problems. This study aimed to determine the cytotoxic effect of picloram on the bioindicator L. culinaris. Nine doses of picloram (0.1, 0.25, 0.5, 0.75, 1, 1.5, 1.5, 2.0, 2.5, and 5 mg/L) were evaluated for their impact on root growth, mitotic index, and frequency of chromosomal abnormalities. Treatment with 5 mg/L picloram significantly inhibited root growth (0.24 ± 0.1 cm, 0.4 ± 0.1 cm, and 0.5 ± 0.15 cm at 24, 48, and 72 h, respectively) and reduced the mitotic index (5.2 ± 10.8), evidencing an interference in cell division. The frequency of chromosomal abnormalities increased with higher concentrations of picloram, suggesting a genotoxic effect even at low concentrations. These findings highlight the need to thoroughly evaluate the effects of herbicides on various aspects of plant development and cellular integrity to gain a more complete understanding of their toxicity and the environmental risks associated with them.