(1) Moreover, lateral root formation can be initiated by the application of the plant hormone auxin .(2) the apex of a growing stem produces auxin(3) The news release relates to auxin , a plant hormone known to function in plant growth and development.(4) Falling levels of plant hormones such as auxin and the cytokinins are responsible.(5) New links to the plant hormone, auxin , were also uncovered.(6) Hormones such as auxins and gibberellins trigger fruit cells to expand.