The tip of a plant root is the where the greatest amount of mitotic activity occurs. The mitotic activity decreases as the distance increases from the plants meristematic region in the root tip.
Since the cells at the plants root cap protect the root and are continuously damaged and scraped away as they grow downward, that region has the greatest need for cells to undergo mitosis in order replace those lost. Root tips are commonly used to study the process of mitosis and the tips of onion, barley, lentil and alfalfa plants are frequent choices for examination. As these represent the most rapidly growing regions of the plant, one can find a great many cells in varying stages of mitosis.