awsone is a compound found in the leaves of the henna plant (Lawsoniainermis). Lawsone has anti-mitotic properties that give it the potential for use as an anti-cancer drug. While most studies on lawsone have been done on animals, this series of experiments was designed to determine if lawsone has an anti-mitotic effect on plants specifically the meristematic cells in onion root tips grown in varying concentrations of this solution. First, the effect of lawsone on root growth and mitotic activity was determined. Next, the effect of higher concentrations on roots was investigated, and a concentration at which root growth is completely inhibited was discovered. Lastly, we ascertained which phase of the cell cycle is inhibited by lawsone, and whether the drug produces any chromosomal abnormalities. Suppression of root growth was found, indicating an anti-mitotic effect, which was supported by lowered mitotic indices. Cells treated with a relatively high concentration of lawsone (1600 μM) failed to divide, while cells exposed to lower concentrations exhibited low mitotic indices, but no noticeable chromosomal abnormalities. Lawsone was found to have a dose-dependent inhibitory effect on mitotic index. Cells at the highest concentration in the last test failed to reach metaphase even with a two-hour colchicine treatment, indicating that lawsone inhibits cell division at some point between interphase and prophase. This latter finding supports previous research that lawsone inhibits mitosis during the S phase of the cell cycle and helps strengthen its position as a potential anti-mitotic treatment and