Auxin

Auxin is a plant hormone that is known to regulate the growth and development of plants. This hormone is produced at the tips of plants. It helps in cell elongation, the growth of roots, and the formation of fruits and flowers. 

Auxin is important to make the plants grow taller and their roots grow deeper in the ground. The hormone also plays a crucial role in influencing the direction of plant growth. Agriculturists use this hormone powder to grow roots from cuttings.