Plant hormones play an integral role in controlling the growth and development of plants.
A problem with this definition is that in all cases plant hormones are not necessarily translocated. A prime example of such a case is the hormone ethylene which may bring about changes in the same tissue or even the same cell in which it is synthesized. Rather than to get caught up in semantics, perhaps a better idea is to outline what a hormone is not. The same is the case for synthesized growth regulatory substances such as 2,4-D regardless of its structure being similar to that of auxin. The definition states that the hormone must be translocated but mentions nothing about how or how far, or even whether it need only cause a response in the cells it is translocated to.