Abstract: Stimulation the in vitro propagation of Guayule from a nutrient medium containing Guayule tissue by adding a substituted trialkyl amine bioinducing agent to the nutrient medium. Selective or differentiated propagation of shoots or callus is obtained by varing the amounts of substituted trialkyl amine present in the nutrient medium. The luxuriant growth provided may be processed for its poly isoprene content or may be transferred to a rooting medium for production of whole plants as identical clones of the original tissue. Provides method for producing large numbers of Guayule plants having identical desirable properties such as high polyisoprene levels.