Cytokinins are organic chemical compounds containing Carbon, Hydrogen and Nitrogen, whose structure resembles that of Adenine. They promote cell division and have other similar functions to Kinetin, which was the first cytokinin discovered and named because of its ability to promote cytokinesis (cell division).

Despite being a natural compound, Kinetin is not made by plants, which leads to it being thought of as a synthetic Cytokinin. (A hormone synthesized somewhere other than in the plant.)

In todays plants the most common form of naturally occurring cytokinin is called Zeatin which was isolated from corn (Zea mays).

Cytokinins have been found in almost all higher plants as well as mosses, fungi, bacteria, and also in the RNA (definition) of many prokaryotes and eukaryotes. Today there are more than 200 natural and synthetic Cytokinins combined. Cytokinin concentrations are highest in meristematic regions.

Meristemic tissue is a type of cellular plant tissue containing non-specialised embryonic cells. It is found in areas of the plant where growth may take place, such as the shoots, buds and roots. Specialised plant cells have a precise set of rules that they follow in order to produce cells of the correct shape, size and structure. Because the plant needs to be adaptable as it grows it uses the meristemic cells in order to alter the shape and structure of the plant body as it grows.

Thus the meristem provides new cells which the plant uses to expand its basic body and form. This allows the plant to maintain its shape and type of structure according to its rules, while still giving leeway for growth. Each of the roots and shoots being able to grow and expand as needed throughout their lifetime.

Because this primary growth is not predetermined by the plants blueprint, the overall shape of the plant is also indeterminate in advance. This gives each meristem the latent ability to develop into a complete plant. As a consequence of this new plants can be grown from cuttings where cells in the broken or cut end change to become specialised root cells. This method of reproduction is called Asexual or Vegetative Reproduction.