Auxin is a plant hormone that promotes growth and development. In this picture, the red dot near the center is a flower bud that contains a lot of the hormone auxin. Auxin also can be found in the meristem and tips of roots and shoots for the plant. It helps with plants growing towards the light (remember phototropism?) because when the plant senses that the stem has more light, it will send more auxin to that area. In addition, auxin helps in repair of the plant, fruit growth, flowering, and apical dominance.